1) The document discusses questions from Class 12 Chemistry chapter on Electrochemistry. It provides answers to questions on topics like redox reactions, galvanic cells, electrode potentials, Nernst equation and conductivity.
2) Calculations are shown to determine standard cell potentials, Gibbs free energy, equilibrium constants and amount of electricity required for various redox reactions.
3) Conductivity and molar conductivity are defined and their variation with concentration is explained for strong and weak electrolytes based on number of ions carrying current.
- The document discusses Bohr's atomic model of hydrogen and its energy levels.
- Bohr proposed that electrons in hydrogen orbit the nucleus in discrete, quantized energy levels and orbits. Only certain orbits are allowed corresponding to specific energy levels.
- Transitions between energy levels result in the emission or absorption of electromagnetic radiation of specific frequencies and wavelengths.
- The energy levels of hydrogen are calculated based on Bohr's model and equations. The ground state has the lowest energy, with increasing energy levels corresponding to higher orbit numbers.
This document presents an overview of the Debye-Huckel limiting law. It explains that in 1923, Peter Debye and Erich Huckel developed a quantitative approach to calculate the mean ionic activity of strong electrolytes. The law relates the logarithm of the mean ionic activity to the ionic strength through the equation log(γ±) = -A√I, where γ± is the mean ionic activity, I is the ionic strength, and A is a constant. Several examples are provided to demonstrate how the law can be applied numerically and graphically for 1:1, 2:1, and 3:1 electrolytes like NaCl, MgCl2, and AgCl3. The key
First part of Statistical Thermodynamics includes: Introduction, Ensembles, Types of Ensembles, Thermodynamic Probability, Boltzmann Distribution, Lagrange's Undetermined Multipliers, Partition Function, Types of Partition Functions, Thermodynamic Properties in terms of partition Function, Heat Capacity, Heat Capacity of Monoatomic Solids, Dulong-Petit law, Einstein Model for solids, 3rd Law and Residual Entropy
Numerical problems on ElectrochemistrySwastika Das
1. The document provides numerical problems and explanations related to electrochemistry concepts like concentration cells, Nernst equation, standard reduction potentials, and calculating cell potentials.
2. Ten sample problems are worked through step-by-step to demonstrate how to calculate cell potentials using concentration, temperature, and standard reduction potential values.
3. The document concludes by providing two sample homework problems for students to practice calculating cell potentials based on given standard electrode potentials and ion concentrations.
Includes a discussion of Voltaic and electrolytic cells, the Nernst equation and the relationship between electrochemical processes, chemical equilibrium and free energy.
**More good stuff available at:
www.wsautter.com
and
http://www.youtube.com/results?search_query=wnsautter&aq=f
Charge-Transfer-Spectra. metal to metal, metal to ligandNafeesAli12
The document discusses charge transfer spectra in metal complexes. There are four main types of charge transfer transitions: ligand to metal (LMCT), metal to ligand (MLCT), intermetal or metal to metal (MMCT), and interligand (LLCT). LMCT involves electron transfer from ligand orbitals to metal orbitals, while MLCT is the reverse with electron transfer from metal to ligand orbitals. MMCT occurs between different oxidation states of the same metal. LLCT takes place between different ligands, one acting as an electron donor and the other as an acceptor. Examples are provided of each type of charge transfer and how they influence the color of complexes.
The document discusses crystal lattices and crystallography concepts including:
- The 14 Bravais lattices that describe the geometric arrangements of points or atoms in crystal structures.
- Miller indices for describing planes in crystal structures.
- Reciprocal lattices and how they relate to direct crystal lattices.
- Symmetry operations and elements that are present in different crystal systems.
- Stereographic projections for representing crystallographic planes and directions.
- The document discusses Bohr's atomic model of hydrogen and its energy levels.
- Bohr proposed that electrons in hydrogen orbit the nucleus in discrete, quantized energy levels and orbits. Only certain orbits are allowed corresponding to specific energy levels.
- Transitions between energy levels result in the emission or absorption of electromagnetic radiation of specific frequencies and wavelengths.
- The energy levels of hydrogen are calculated based on Bohr's model and equations. The ground state has the lowest energy, with increasing energy levels corresponding to higher orbit numbers.
This document presents an overview of the Debye-Huckel limiting law. It explains that in 1923, Peter Debye and Erich Huckel developed a quantitative approach to calculate the mean ionic activity of strong electrolytes. The law relates the logarithm of the mean ionic activity to the ionic strength through the equation log(γ±) = -A√I, where γ± is the mean ionic activity, I is the ionic strength, and A is a constant. Several examples are provided to demonstrate how the law can be applied numerically and graphically for 1:1, 2:1, and 3:1 electrolytes like NaCl, MgCl2, and AgCl3. The key
First part of Statistical Thermodynamics includes: Introduction, Ensembles, Types of Ensembles, Thermodynamic Probability, Boltzmann Distribution, Lagrange's Undetermined Multipliers, Partition Function, Types of Partition Functions, Thermodynamic Properties in terms of partition Function, Heat Capacity, Heat Capacity of Monoatomic Solids, Dulong-Petit law, Einstein Model for solids, 3rd Law and Residual Entropy
Numerical problems on ElectrochemistrySwastika Das
1. The document provides numerical problems and explanations related to electrochemistry concepts like concentration cells, Nernst equation, standard reduction potentials, and calculating cell potentials.
2. Ten sample problems are worked through step-by-step to demonstrate how to calculate cell potentials using concentration, temperature, and standard reduction potential values.
3. The document concludes by providing two sample homework problems for students to practice calculating cell potentials based on given standard electrode potentials and ion concentrations.
Includes a discussion of Voltaic and electrolytic cells, the Nernst equation and the relationship between electrochemical processes, chemical equilibrium and free energy.
**More good stuff available at:
www.wsautter.com
and
http://www.youtube.com/results?search_query=wnsautter&aq=f
Charge-Transfer-Spectra. metal to metal, metal to ligandNafeesAli12
The document discusses charge transfer spectra in metal complexes. There are four main types of charge transfer transitions: ligand to metal (LMCT), metal to ligand (MLCT), intermetal or metal to metal (MMCT), and interligand (LLCT). LMCT involves electron transfer from ligand orbitals to metal orbitals, while MLCT is the reverse with electron transfer from metal to ligand orbitals. MMCT occurs between different oxidation states of the same metal. LLCT takes place between different ligands, one acting as an electron donor and the other as an acceptor. Examples are provided of each type of charge transfer and how they influence the color of complexes.
The document discusses crystal lattices and crystallography concepts including:
- The 14 Bravais lattices that describe the geometric arrangements of points or atoms in crystal structures.
- Miller indices for describing planes in crystal structures.
- Reciprocal lattices and how they relate to direct crystal lattices.
- Symmetry operations and elements that are present in different crystal systems.
- Stereographic projections for representing crystallographic planes and directions.
This document discusses various types of defects that can occur in crystalline solids, including point defects, line defects (dislocations), two-dimensional defects (surfaces and interfaces), and volume defects. It focuses on point defects such as vacancies, interstitials, and solute/impurity atoms. Intrinsic point defects include vacancies and interstitials, while extrinsic defects are caused by solute/impurity atoms. These defects can have significant effects on properties like electrical conductivity in semiconductors and mechanical strength in structural alloys.
Lecture 8: Introduction to Quantum Chemical Simulation graduate course taught at MIT in Fall 2014 by Heather Kulik. This course covers: wavefunction theory, density functional theory, force fields and molecular dynamics and sampling.
Non-Stoichiometry & Solid Solution
The document discusses various types of point defects that can occur in non-stoichiometric compounds including Schottky defects, Frenkel defects, and anti-site defects. It provides examples of intrinsic point defects in metal-deficient, metal-excess, oxygen-deficient, and oxygen-excess metal oxides. Solid solutions are formed when one or more minor components dissolve uniformly within the crystal lattice of a major component. Types of solid solutions include interstitial, substitutional, ordered, and disordered solutions. Experimental techniques like X-ray diffraction and density measurements can be used to study properties of non-stoichiometric compounds and solid solutions.
The document provides an overview of key concepts in electrochemistry including:
1) The components and operation of electrochemical cells including voltaic cells like batteries and fuel cells as well as electrolytic cells.
2) Half-reactions, electrode potentials, and using these to determine spontaneity of redox reactions.
3) Processes like corrosion, electroplating, electrolysis of water, and recharging of batteries that involve redox reactions driven by electrical energy.
The document discusses shielding and screening in atoms. Shielding refers to the reduction of the true nuclear charge on the atom's nucleus by the electrons in other orbitals. Screening is the same concept as shielding. The effective nuclear charge (Zeff) experienced by an electron is calculated as Zeff = Z - σ, where Z is the atomic number and σ is the shielding constant. While the energy of an electron is proportional to Z2/n2, the energy required to remove an electron does not continuously increase with atomic number due to shielding effects of inner electrons.
The document discusses the Schrodinger equation of the hydrogen atom. It shows how the Schrodinger equation can be separated into radial and angular variables using spherical coordinates. This results in three ordinary differential equations - one for the radial coordinate and two for the angular coordinates. The solutions of these equations involve quantum numbers such as the orbital angular momentum quantum number l and its magnetic quantum number ml.
(10) electron spin & angular momentum couplingIbenk Hallen
- Electrons have intrinsic angular momentum called spin. Spin takes values of ±1/2.
- Pauli exclusion principle states that no two electrons in an atom can have the same set of quantum numbers (n, l, ml, ms).
- Atomic orbitals are characterized by principal quantum number n, azimuthal quantum number l, and magnetic quantum number ml.
- Electrons first fill up lowest energy orbitals according to Aufbau principle.
- Spin-orbit coupling arises from the interaction of an electron's magnetic moment with the magnetic field generated by the nucleus. This leads to splitting of energy levels.
Schrodinger equation and its applications: Chapter 2Dr.Pankaj Khirade
Wave function and its physical significance, Schrodinger time dependent equation, Separation in time dependent and time independent parts, Operators in quantum Mechanics, Eigen functions and Eigen values, Particle in one dimensional and three dimensional box (Energy eigen values). Qualitative analysis of potential barrier Tunneling effect). Simple Harmonic Oscillator (Qualitative analysis of Zero point energy)
This document discusses potentials and fields in electrostatics and electrodynamics. It introduces vector and scalar potentials, gauge transformations, and Maxwell's equations in potential form. It then covers plane wave solutions to Maxwell's equations using potentials. Retarded potentials are defined using the retarded time, and it is shown that the retarded potentials satisfy Maxwell's equations in the Lorentz gauge. Finally, it discusses Lienard-Wiechert potentials for point charges and approaches to deriving length contraction and other relativistic effects from potentials and fields.
Part 4, Substitution reactions in square planar complexes, Theories of Trans ...Geeta Tewari
This document discusses theories of the trans effect in square planar complexes. It describes how the trans effect was discovered and causes ligands trans to certain spectator ligands to be more reactive. The polarization theory explains that polarizable ligands induce a dipole in the metal, weakening bonds to ligands on the trans side. The π-bonding theory explains that π-acceptor ligands accept electron density from the metal, also weakening trans bonds. Both theories agree that a weaker trans bond lowers the activation energy for substitution reactions.
Crystal field theory and ligand field theory describe how ligands interact with transition metal complexes. Crystal field theory uses an electrostatic model to explain orbital splitting, while ligand field theory uses a molecular orbital approach. Both theories predict that ligands cause the d orbitals on the metal to split into lower energy t2g and higher energy eg sets. The size of this splitting depends on whether ligands are σ-donors only, π-donors, or π-acceptors. π-Acceptors increase splitting while π-donors decrease it. This explains the spectrochemical series from weak to strong field ligands.
This document discusses evidence for covalent bonding in metal complexes. It explains that electron-electron repulsion is less in complexes than free metal ions due to delocalization of electrons over ligand orbitals. This is known as the nephelauxetic effect. The nephelauxetic parameter (β) quantifies this effect, with softer ligands having a smaller β value. Electron paramagnetic resonance (EPR) spectroscopy provides further evidence, as the spectra of complexes show interaction between the ligand nuclear spin and electrons of the metal ion.
This document discusses the optical properties of solids. It begins by defining optical properties as light-matter interactions like reflection, absorption, transmission and refraction. Optical processes are classified into reflection, propagation and transmission. Key optical parameters discussed include refractive index, absorption coefficient, dielectric constant, and complex refractive index. Beer's law relating light intensity and absorption is explained. The properties of insulators, semiconductors, glasses and metals are then summarized. Insulators and semiconductors are highly transmitting in visible ranges with absorption in UV and IR. Glasses like fused silica are also highly transmitting but with shorter ranges. Metals are highly reflective across most frequencies.
The document discusses various electrolytic processes including electrolysis of molten aluminum and electroplating of gold, silver, and lead. It explains that electrolysis uses electricity to drive chemical reactions like the reduction of aluminum ions to produce aluminum metal at the cathode. Impure metals can also be refined through electrorefining which uses electrolysis to oxidize impurities at the anode while reducing the desired metal at the cathode.
This document provides an overview of physical chemistry and its branches, which include thermodynamics, quantum chemistry, statistical mechanics, and kinetics. It discusses various concepts in physical chemistry such as thermodynamic systems and properties, the laws of thermodynamics, entropy, Gibbs free energy, and thermodynamic calculations. Key areas covered are the branches of physical chemistry and why it is important for chemical engineers, as well as explanations of concepts like thermodynamic equilibrium, state functions, and the measurement of temperature.
UCSD NANO 266 Quantum Mechanical Modelling of Materials and Nanostructures is a graduate class that provides students with a highly practical introduction to the application of first principles quantum mechanical simulations to model, understand and predict the properties of materials and nano-structures. The syllabus includes: a brief introduction to quantum mechanics and the Hartree-Fock and density functional theory (DFT) formulations; practical simulation considerations such as convergence, selection of the appropriate functional and parameters; interpretation of the results from simulations, including the limits of accuracy of each method. Several lab sessions provide students with hands-on experience in the conduct of simulations. A key aspect of the course is in the use of programming to facilitate calculations and analysis.
This document provides an introduction to rotational spectra and microwave spectroscopy. It discusses the rotational spectra of rigid diatomic molecules, classification of molecules, selection rules, and moments of inertia. The key points are:
1) Rotational spectra are obtained from transitions between rotational energy levels within the same vibrational state, giving information about molecular parameters.
2) Molecules are classified based on their principal moments of inertia as linear, symmetric top, spherical top, or asymmetric top.
3) The rotational energy levels and spectra of rigid diatomic molecules can be described using a rigid rotor model based on the molecular moment of inertia.
4) The selection rule for rotational transitions in a rigid diatomic molecule is that
The document discusses molecular geometry and hybridization of atomic orbitals. It introduces the valence shell electron pair repulsion (VSEPR) model, which predicts molecular geometry based on electron pair repulsions. Molecular geometry is determined by counting bonding pairs and lone pairs on the central atom. Hybridization involves mixing atomic orbitals to form new hybrid orbitals and explains the geometry of molecules like methane and boron trifluoride. Polar molecules form if there is an uneven distribution of charge, while nonpolar molecules have symmetrical charge distribution.
1. Hartree-Fock theory describes molecules using a linear combination of atomic orbitals to approximate molecular orbitals. It treats electrons as independent particles moving in the average field of other electrons.
2. The Hartree-Fock method involves iteratively solving the Fock equations until self-consistency is reached between the input and output orbitals. This approximates electron correlation by including an average electron-electron repulsion term.
3. The Hartree-Fock method satisfies the Pauli exclusion principle through the use of Slater determinants, which are antisymmetric wavefunctions that go to zero when the spatial or spin coordinates of any two electrons are identical.
Electrolysis is the process of using direct electrical current to cause a non-spontaneous chemical reaction. During electrolysis, ions conduct electricity and move towards the electrode that attracts them. The key factors that determine the products of electrolysis include:
1) The type of electrolyte, whether it is a molten salt or aqueous solution, determines which ions are present and can be reduced or oxidized.
2) An ion's position in the electrochemical series indicates its tendency to gain or lose electrons. Ions lower in the series are more readily reduced or oxidized.
3) The concentration of the electrolyte solution can allow ions higher in the electrochemical series to also be reduced or
This document discusses various types of defects that can occur in crystalline solids, including point defects, line defects (dislocations), two-dimensional defects (surfaces and interfaces), and volume defects. It focuses on point defects such as vacancies, interstitials, and solute/impurity atoms. Intrinsic point defects include vacancies and interstitials, while extrinsic defects are caused by solute/impurity atoms. These defects can have significant effects on properties like electrical conductivity in semiconductors and mechanical strength in structural alloys.
Lecture 8: Introduction to Quantum Chemical Simulation graduate course taught at MIT in Fall 2014 by Heather Kulik. This course covers: wavefunction theory, density functional theory, force fields and molecular dynamics and sampling.
Non-Stoichiometry & Solid Solution
The document discusses various types of point defects that can occur in non-stoichiometric compounds including Schottky defects, Frenkel defects, and anti-site defects. It provides examples of intrinsic point defects in metal-deficient, metal-excess, oxygen-deficient, and oxygen-excess metal oxides. Solid solutions are formed when one or more minor components dissolve uniformly within the crystal lattice of a major component. Types of solid solutions include interstitial, substitutional, ordered, and disordered solutions. Experimental techniques like X-ray diffraction and density measurements can be used to study properties of non-stoichiometric compounds and solid solutions.
The document provides an overview of key concepts in electrochemistry including:
1) The components and operation of electrochemical cells including voltaic cells like batteries and fuel cells as well as electrolytic cells.
2) Half-reactions, electrode potentials, and using these to determine spontaneity of redox reactions.
3) Processes like corrosion, electroplating, electrolysis of water, and recharging of batteries that involve redox reactions driven by electrical energy.
The document discusses shielding and screening in atoms. Shielding refers to the reduction of the true nuclear charge on the atom's nucleus by the electrons in other orbitals. Screening is the same concept as shielding. The effective nuclear charge (Zeff) experienced by an electron is calculated as Zeff = Z - σ, where Z is the atomic number and σ is the shielding constant. While the energy of an electron is proportional to Z2/n2, the energy required to remove an electron does not continuously increase with atomic number due to shielding effects of inner electrons.
The document discusses the Schrodinger equation of the hydrogen atom. It shows how the Schrodinger equation can be separated into radial and angular variables using spherical coordinates. This results in three ordinary differential equations - one for the radial coordinate and two for the angular coordinates. The solutions of these equations involve quantum numbers such as the orbital angular momentum quantum number l and its magnetic quantum number ml.
(10) electron spin & angular momentum couplingIbenk Hallen
- Electrons have intrinsic angular momentum called spin. Spin takes values of ±1/2.
- Pauli exclusion principle states that no two electrons in an atom can have the same set of quantum numbers (n, l, ml, ms).
- Atomic orbitals are characterized by principal quantum number n, azimuthal quantum number l, and magnetic quantum number ml.
- Electrons first fill up lowest energy orbitals according to Aufbau principle.
- Spin-orbit coupling arises from the interaction of an electron's magnetic moment with the magnetic field generated by the nucleus. This leads to splitting of energy levels.
Schrodinger equation and its applications: Chapter 2Dr.Pankaj Khirade
Wave function and its physical significance, Schrodinger time dependent equation, Separation in time dependent and time independent parts, Operators in quantum Mechanics, Eigen functions and Eigen values, Particle in one dimensional and three dimensional box (Energy eigen values). Qualitative analysis of potential barrier Tunneling effect). Simple Harmonic Oscillator (Qualitative analysis of Zero point energy)
This document discusses potentials and fields in electrostatics and electrodynamics. It introduces vector and scalar potentials, gauge transformations, and Maxwell's equations in potential form. It then covers plane wave solutions to Maxwell's equations using potentials. Retarded potentials are defined using the retarded time, and it is shown that the retarded potentials satisfy Maxwell's equations in the Lorentz gauge. Finally, it discusses Lienard-Wiechert potentials for point charges and approaches to deriving length contraction and other relativistic effects from potentials and fields.
Part 4, Substitution reactions in square planar complexes, Theories of Trans ...Geeta Tewari
This document discusses theories of the trans effect in square planar complexes. It describes how the trans effect was discovered and causes ligands trans to certain spectator ligands to be more reactive. The polarization theory explains that polarizable ligands induce a dipole in the metal, weakening bonds to ligands on the trans side. The π-bonding theory explains that π-acceptor ligands accept electron density from the metal, also weakening trans bonds. Both theories agree that a weaker trans bond lowers the activation energy for substitution reactions.
Crystal field theory and ligand field theory describe how ligands interact with transition metal complexes. Crystal field theory uses an electrostatic model to explain orbital splitting, while ligand field theory uses a molecular orbital approach. Both theories predict that ligands cause the d orbitals on the metal to split into lower energy t2g and higher energy eg sets. The size of this splitting depends on whether ligands are σ-donors only, π-donors, or π-acceptors. π-Acceptors increase splitting while π-donors decrease it. This explains the spectrochemical series from weak to strong field ligands.
This document discusses evidence for covalent bonding in metal complexes. It explains that electron-electron repulsion is less in complexes than free metal ions due to delocalization of electrons over ligand orbitals. This is known as the nephelauxetic effect. The nephelauxetic parameter (β) quantifies this effect, with softer ligands having a smaller β value. Electron paramagnetic resonance (EPR) spectroscopy provides further evidence, as the spectra of complexes show interaction between the ligand nuclear spin and electrons of the metal ion.
This document discusses the optical properties of solids. It begins by defining optical properties as light-matter interactions like reflection, absorption, transmission and refraction. Optical processes are classified into reflection, propagation and transmission. Key optical parameters discussed include refractive index, absorption coefficient, dielectric constant, and complex refractive index. Beer's law relating light intensity and absorption is explained. The properties of insulators, semiconductors, glasses and metals are then summarized. Insulators and semiconductors are highly transmitting in visible ranges with absorption in UV and IR. Glasses like fused silica are also highly transmitting but with shorter ranges. Metals are highly reflective across most frequencies.
The document discusses various electrolytic processes including electrolysis of molten aluminum and electroplating of gold, silver, and lead. It explains that electrolysis uses electricity to drive chemical reactions like the reduction of aluminum ions to produce aluminum metal at the cathode. Impure metals can also be refined through electrorefining which uses electrolysis to oxidize impurities at the anode while reducing the desired metal at the cathode.
This document provides an overview of physical chemistry and its branches, which include thermodynamics, quantum chemistry, statistical mechanics, and kinetics. It discusses various concepts in physical chemistry such as thermodynamic systems and properties, the laws of thermodynamics, entropy, Gibbs free energy, and thermodynamic calculations. Key areas covered are the branches of physical chemistry and why it is important for chemical engineers, as well as explanations of concepts like thermodynamic equilibrium, state functions, and the measurement of temperature.
UCSD NANO 266 Quantum Mechanical Modelling of Materials and Nanostructures is a graduate class that provides students with a highly practical introduction to the application of first principles quantum mechanical simulations to model, understand and predict the properties of materials and nano-structures. The syllabus includes: a brief introduction to quantum mechanics and the Hartree-Fock and density functional theory (DFT) formulations; practical simulation considerations such as convergence, selection of the appropriate functional and parameters; interpretation of the results from simulations, including the limits of accuracy of each method. Several lab sessions provide students with hands-on experience in the conduct of simulations. A key aspect of the course is in the use of programming to facilitate calculations and analysis.
This document provides an introduction to rotational spectra and microwave spectroscopy. It discusses the rotational spectra of rigid diatomic molecules, classification of molecules, selection rules, and moments of inertia. The key points are:
1) Rotational spectra are obtained from transitions between rotational energy levels within the same vibrational state, giving information about molecular parameters.
2) Molecules are classified based on their principal moments of inertia as linear, symmetric top, spherical top, or asymmetric top.
3) The rotational energy levels and spectra of rigid diatomic molecules can be described using a rigid rotor model based on the molecular moment of inertia.
4) The selection rule for rotational transitions in a rigid diatomic molecule is that
The document discusses molecular geometry and hybridization of atomic orbitals. It introduces the valence shell electron pair repulsion (VSEPR) model, which predicts molecular geometry based on electron pair repulsions. Molecular geometry is determined by counting bonding pairs and lone pairs on the central atom. Hybridization involves mixing atomic orbitals to form new hybrid orbitals and explains the geometry of molecules like methane and boron trifluoride. Polar molecules form if there is an uneven distribution of charge, while nonpolar molecules have symmetrical charge distribution.
1. Hartree-Fock theory describes molecules using a linear combination of atomic orbitals to approximate molecular orbitals. It treats electrons as independent particles moving in the average field of other electrons.
2. The Hartree-Fock method involves iteratively solving the Fock equations until self-consistency is reached between the input and output orbitals. This approximates electron correlation by including an average electron-electron repulsion term.
3. The Hartree-Fock method satisfies the Pauli exclusion principle through the use of Slater determinants, which are antisymmetric wavefunctions that go to zero when the spatial or spin coordinates of any two electrons are identical.
Electrolysis is the process of using direct electrical current to cause a non-spontaneous chemical reaction. During electrolysis, ions conduct electricity and move towards the electrode that attracts them. The key factors that determine the products of electrolysis include:
1) The type of electrolyte, whether it is a molten salt or aqueous solution, determines which ions are present and can be reduced or oxidized.
2) An ion's position in the electrochemical series indicates its tendency to gain or lose electrons. Ions lower in the series are more readily reduced or oxidized.
3) The concentration of the electrolyte solution can allow ions higher in the electrochemical series to also be reduced or
This document discusses a lecture on electrochemistry. It covers key concepts like electrolysis, Faraday's laws of electrolysis, and electrochemical cells.
Some key points covered include that electrolysis is the decomposition of a compound by an electric current, and involves oxidation and reduction reactions. Faraday's first law states the mass of a substance produced by electrolysis is directly proportional to the quantity of electricity used. Faraday's second law relates the masses of different substances deposited to their equivalent masses. An electrochemical cell uses a redox reaction to produce an electrical current.
The document discusses electrochemistry and electrolysis. It defines electrolytes and non-electrolytes, and explains how electrolytes can conduct electricity in molten or aqueous states through the movement of ions. Examples are given of electrolysis processes and how electrolysis can be used for metal extraction, purification, and electroplating.
This document provides an overview of electrochemistry. It begins by defining electrochemistry as the study of chemical reactions at the interface of an electrode and electrolyte involving the interaction of electrical and chemical changes. The document then discusses the history and founders of electrochemistry, including Faraday's two laws of electrolysis. It explains key concepts such as oxidation-reduction reactions, balancing redox equations, and the Nernst equation. The document also covers applications including batteries, corrosion, electrolysis, and branches of electrochemistry like bioelectrochemistry and nanoelectrochemistry.
- The elements in Group 15 show increasing covalent radius and decreasing ionization energy down the group, due to additional shells. Nitrogen behaves anomalously due to small size and high electronegativity.
- They form trihydrides (MH3), trioxides (M2O3), and pentoxides (M2O5) with decreasing acidity down the group. They also form trihalides and pentahalides.
- Oxygen is industrially produced from air or water and is essential for respiration and combustion. Ozone is a reactive allotrope produced from oxygen that is used for sterilization and bleaching.
The document describes calculating the cell potential of a galvanic cell made by coupling a standard Zn/Zn2+ electrode to a standard hydrogen electrode at 25°C, where the hydrogen electrode is buffered to pH=5.57. Using the Nernst equation, the resulting cell potential is calculated to be 0.434 V.
Structure of atom exercise -with solutionssuresh gdvm
This document contains solved problems related to atomic structure and quantum mechanics. Some key points:
- It calculates the number of electrons that weigh 1 gram and the mass and charge of 1 mole of electrons.
- It finds the number of protons, electrons, and neutrons in various atoms and isotopes.
- It calculates properties like wavelength, frequency, wave number, and energy for photons and electromagnetic radiation.
- It determines the ionization energy of sodium using the wavelength of radiation required to ionize sodium atoms.
- Problems also deal with work function, photoelectron velocity, electron transitions in hydrogen atoms, and the maximum possible emission lines when an electron in the n=6 orbital drops to the ground
This document contains sample questions and answers related to Chapter 4 - Chemical Kinetics from the NCERT Class XII Chemistry textbook. It includes 10 multiple choice questions about rate of reaction, order of reaction, rate constants, effect of temperature and concentration on rate, pseudo-first order kinetics, and determining the order of a reaction based on initial rate data. The questions cover concepts such as rate laws, rate equations, integrated rate laws, half-life of reactions, activation energy, Arrhenius equation and their applications to calculate rates, concentrations, times, constants and orders of reactions.
This document provides answers to questions about electric current and resistance from Chapter 27. It includes calculations of current, resistance, resistivity, and other electrical properties. Key points addressed include:
- How geometry and temperature affect resistance
- Models for electrical conduction and how resistance changes with temperature
- Properties of superconductors and electrical power calculations
- Questions cover topics like current density, resistivity, Ohm's law, and resistances of different materials.
This document contains questions and answers related to atomic and nuclear physics concepts. Some key points:
- The uppermost energy level in a diagram is n=infinity with E=0, and the lowest is n=1 with E=-13.6eV.
- Transitions in the Balmer series end at the n=2 level.
- Breeder reactors convert fertile material into fissile material.
- MRI stands for magnetic resonance imaging and uses nuclear magnetic resonance principles.
- Several questions provide calculations to determine transition wavelengths, energy levels, radioactive decay rates, and energy released in nuclear reactions.
Beaker A contained 0.74 g Ca(OH)2 in 100 ml water. This amount is less than the saturation point of 0.0814 g/100 ml. So the solution was unsaturated.
Beaker B contained 1.48 g Ca(OH)2 in 100 ml water. This amount exceeds the saturation point. So the solution was saturated.
The conductivity and pH would be higher in the saturated solution in Beaker B compared to the unsaturated solution in Beaker A. This is because in a saturated solution, more Ca2+ and OH- ions are available to carry current and increase pH respectively.
So the solution in Beaker B would be more conductive and have a higher pH value than
This document provides an overview of electrochemistry and electrolytic cells. It discusses:
- Electrochemistry involves the study of redox reactions and the transfer of electrons, including oxidation which is the loss of electrons and reduction which is the gain of electrons.
- Electrolytic cells use electrical energy to drive redox reactions in a direction that does not occur spontaneously, with examples of cathode and anode half reactions.
- Quantitative electrolysis allows control over the amount of substance undergoing a reaction, according to Faraday's laws - the amount of reaction is proportional to the charge passed, and different electrolytes require different amounts of electrons for the same reaction.
- An example problem calculates the mass of copper
1. Electrolyte solutions conduct electricity due to the presence of ions. Strong electrolytes fully dissociate into ions in solution, while weak electrolytes only partially dissociate.
2. Ion transport in electrolyte solutions occurs through diffusion due to concentration gradients and migration due to applied electric fields. Conductivity and molar conductivity describe how well solutions conduct, and depend on factors like ion type and concentration.
3. At infinite dilution, the limiting molar conductivity of electrolytes can be calculated from the ion mobilities. For concentrated solutions, effects like ion-ion interactions cause conductivity to decrease with concentration.
This document summarizes key concepts from an electrochemistry chapter, including:
- Redox reactions involve the gain or loss of electrons. Voltaic cells harness redox reactions to produce electric currents.
- Standard reduction potentials indicate the tendency of half-reactions to gain or lose electrons under standard conditions.
- Electrochemical cells use spontaneous redox reactions to generate voltage. Applications include batteries, electrolysis, corrosion prevention, and pH meters.
This document provides an overview of key concepts in electrochemistry, including:
- Galvanic cells use spontaneous chemical reactions to generate electrical energy, while electrolytic cells use an applied voltage to drive nonspontaneous reactions.
- Cell potentials and the Nernst equation relate the standard cell potential to non-standard state potentials based on reaction quotients.
- Faraday's law of electrolysis states that the amount of product formed is proportional to the quantity of electricity passed, as measured by coulombs of charge.
- Standard reduction potentials and Gibbs free energy can be used to determine cell potentials and predict spontaneity of redox reactions.
This document provides an overview of key concepts in electrochemistry, including:
- Galvanic cells use spontaneous chemical reactions to generate electrical energy, while electrolytic cells use an applied voltage to drive nonspontaneous reactions.
- Oxidation occurs at the anode and reduction at the cathode. Standard cell potential and Faraday's law relate the electrical work done to chemical reactions.
- Faraday's law states that the amount of product formed during electrolysis is directly proportional to the charge passed, allowing calculations of moles reacted given current and time.
- Standard cell potential and the Nernst equation describe how cell potential varies with reaction conditions versus under standard states.
This document contains a chemistry exam for Class XII with 24 questions testing various concepts. It includes multiple choice questions, very short answer questions, short answer questions, and long answer questions testing topics like electrochemistry, kinetics, properties of elements and ions, and redox reactions. The exam has a total mark of 30 and a duration of 90 minutes.
Career Point JEE Advanced Solution Paper1askiitians
1. The document is a past exam paper for the JEE Advanced exam with questions related to physics.
2. It contains 10 multiple choice questions in the first section testing concepts like projectile motion, lenses, measurement using vernier callipers, work done by a force, stress-strain relationship, reflection of light, heat conduction, momentum transfer by light, interference patterns, and properties of ideal gases.
3. The second section has 5 multi-select questions related to electric fields of charged spheres, harmonic motion of a vibrating string, and charging of parallel plate capacitors.
This document provides detailed solutions to the 2013 JEE Advanced Paper 1 with code 0. It contains solutions to 10 multiple choice questions in Section 1 and 5 multiple choice questions in Section 2 of the Physics portion of the exam. The solutions explain the conceptual reasoning and calculations for arriving at the correct answers. Key details provided in the solutions include relevant equations, diagrams, and step-by-step working.
1. The document contains a physics exam with 16 multiple choice questions covering topics like mechanics, electromagnetism, thermodynamics, and modern physics.
2. Question 1 asks about the pressure required to keep a steel wire at a constant length when its temperature increases by 100°C based on the wire's properties.
3. Several other questions ask about concepts like angular momentum, diode current-voltage characteristics, electromagnetic waves, capacitors, simple harmonic motion, electromagnetic induction, and kinematics for particles in vertical motion.
1. The document contains solved problems related to solutions from Class 12 Chemistry Chapter 2.
2. It discusses concepts like mass percentage, mole fraction, molarity, molality, vapour pressure, boiling point elevation, freezing point depression and osmotic pressure.
3. Various types of problems are solved which involve calculating quantities related to solutions using concepts like Raoult's law and Henry's law.
Half-reactions indicate the mole ratio of electrons to ions involved in redox reactions. The document discusses how current, time, and charge are related based on 1 mole of electrons equating to 96,500 Coulombs of charge. It provides examples calculating the mass of copper produced from electrolysis and the volume of chlorine gas produced from an industrial electrolysis process based on given values of current and time.
1. The document contains a practice exam with 37 multiple choice questions covering concepts in thermodynamics and chemistry. The questions cover topics like ideal gases, enthalpy, entropy, spontaneity of reactions, and more.
2. For each question there are 4 possible answers labeled a-d. The correct answers are not provided.
3. The questions are intended to test understanding of fundamental thermodynamic concepts and calculations involving things like heat, work, internal energy, and state functions.
Thermodynamics is the study of heat and work, and state functions. Energy exists in various forms including heat, light, electrical, and kinetic and potential. Heat is the transfer of energy between objects due to a temperature difference. Chemical reactions can be exothermic or endothermic depending on the direction of heat transfer. The total energy in a chemical system is conserved according to the law of conservation of energy. Changes in potential and kinetic energy account for temperature changes in chemical processes.
1. Chemical thermodynamics deals with energy changes that occur during chemical reactions and processes involving chemical substances.
2. It helps determine the feasibility and extent of chemical reactions and processes under given conditions based on fundamental laws of physical chemistry.
3. Key concepts include the various types of systems (open, closed, isolated), state functions, state variables, and different thermodynamic processes (isothermal, adiabatic, isobaric, isochoric).
States of matter can exist as solids, liquids, or gases. Gases have no definite shape or volume, are highly compressible, and their molecules are far apart with weak intermolecular forces. Liquids have a definite volume but no definite shape, while solids have both a definite shape and volume. The behavior of gases is explained by gas laws such as Boyle's law, Charles's law, Avogadro's law, Dalton's law of partial pressures, Graham's law of diffusion, and the ideal gas law. Gases can be liquefied under high pressure and low temperature due to intermolecular attractions that cause real gases to deviate from ideal behavior.
Gases are composed of tiny particles that are in constant, random motion. Three properties of gases are pressure, volume, and temperature. The kinetic molecular theory and gas laws describe the relationships between these properties. The ideal gas law combines earlier gas laws relating pressure, volume, amount of gas, and temperature into a single equation.
The document discusses the characteristics and properties of gases. It defines the gaseous state as the state where intermolecular forces are at a minimum. Some key characteristics of gases include having low density, high compressibility, diffusibility, and filling their container uniformly. The document also discusses various gas laws including Boyle's law, Charles' law, Gay-Lussac's law, Avogadro's law, and the ideal gas equation. It provides the mathematical relationships and graphical representations for each gas law.
The document contains multiple choice questions about gas laws, kinetic molecular theory, and properties of gases.
1) Questions ask about calculating properties like density and pressure given temperature, volume, amount of gas, and other variables.
2) Other questions relate to concepts like effusion rates, van der Waals constants, and the relationship between temperature, pressure, volume, and number of gas molecules.
3) Graphs and diagrams are included that must be interpreted in the context of gas behavior and equations of state.
This document discusses chemical bonding and dipole moments. It contains questions about the units of dipole moment, molecules with zero dipole moment, factors that determine whether a molecule has a dipole moment, and bond properties like bond length, bond energy, and hybridization.
Chemical bonding results from the attraction between nuclei and electrons. There are three main types of bonding: ionic, covalent, and metallic. Ionic bonding involves the transfer of electrons between atoms to form ions. Covalent bonding involves the sharing of electron pairs between atoms. Metallic bonding occurs between metal atoms through delocalized valence electrons. The type of bonding determines the physical properties of the substance.
This document discusses chemical bonding and molecular structure. It begins by explaining that atoms combine through chemical bonds to form molecules and different theories have sought to explain why certain combinations are possible and what determines molecular shapes. It then summarizes Kössel-Lewis approach to chemical bonding, which proposed that atoms achieve stability by gaining or sharing electrons to attain a full outer shell of 8 electrons. Covalent bonds are formed by shared pairs of electrons between atoms. Lewis structures use dots to represent valence electrons and predict molecular geometry.
This document discusses the structure of atoms and the types of chemical bonds. It begins by defining the atom and its components like protons, electrons, and electron shells. It then explains the three main types of chemical bonds: ionic bonds formed between ions through electron transfer, covalent bonds formed by electron sharing, and metallic bonds in metals involving delocalized electrons. Some key points about each bond type are given, like ion formation and electron configuration changes. Examples of each bond type are provided. Formulas for ionic compounds and determining formula weights are also covered.
This document discusses different types of chemical bonds including ionic, covalent, and metallic bonds. It describes the formation of ionic bonds between metals and nonmetals and how ionization energy, electron affinity, and lattice energy contribute to the energetics of ionic bonding. Covalent bonding is explained as the sharing of electrons between nonmetals. Factors that determine bond polarity like electronegativity are also covered. The document provides details on writing Lewis structures, accounting for valence electrons and formal charges. Exceptions to the octet rule for molecules with odd numbers of electrons, incomplete octets, and expanded octets are explained.
Chemical bonding occurs when atoms combine to form molecules or ionic compounds to achieve stable electronic configurations. There are several types of bonds including ionic bonds, covalent bonds, and coordinate bonds. Ionic bonds form when electrons are transferred from electropositive atoms to electronegative atoms, resulting in oppositely charged ions that are attracted to each other. Covalent bonds form through the sharing of electron pairs between atoms. Coordinate bonds form through the interaction of a Lewis acid and base where one species provides a pair of electrons. Chemical bonds provide stability and determine many properties of substances.
The document discusses the evolution and development of the periodic table. It describes early classification systems like Dobereiner's law of triads and Newlands' law of octaves. It then focuses on Mendeleev's periodic table from 1869, which was the first significant classification based on atomic mass. The modern periodic table is based on atomic number rather than mass, resolving anomalies in Mendeleev's table. It discusses periodic trends in properties like atomic radius and how the periodic table is structured into blocks, periods and groups.
The document discusses periodic trends in elemental properties. It explains that Dmitri Mendeleev was the first to organize elements in a periodic table based on their properties. Elements in the same group have similar properties due to their valence electrons. Atomic radius generally decreases moving left to right across a period and increases moving down a group due to electron shielding. Ionization energy increases as atomic radius decreases. Electron affinity is exothermic when gaining electrons fills an orbital. Metallic character decreases and electronegativity increases moving from left to right. Cations are smaller than their parent atoms while anions are larger.
This document provides information on the classification of elements and various periodic properties like atomic size, ionization energy, electron affinity and electronegativity. It discusses the trends in these properties across periods and groups and exceptions to trends. It also explains concepts like ionic size, isoelectronic species, ionization energies, electron affinities, Pauling and Mulliken scales of electronegativity and valency. Sample problems are provided at the end to test the understanding of these concepts.
This document summarizes key concepts in atomic structure:
1. It outlines the early theories of Dalton, Thomson, Rutherford, and Bohr, which proposed that atoms are made of fundamental particles and have small, dense nuclei surrounded by orbiting electrons.
2. It describes experiments that discovered the electron and properties of cathode rays. Rutherford's gold foil experiment provided evidence for a small, dense nucleus.
3. Quantum theory concepts like Planck's quantum hypothesis, Bohr's model of electron orbits, and de Broglie's matter waves are introduced along with equations relating wavelength, frequency and energy of photons.
This document provides an overview of basic chemistry concepts. It begins by classifying matter as either mixtures or pure substances, with pure substances further divided into elements and compounds. Elements contain only one type of atom, while compounds contain two or more different types of atoms combined in fixed ratios. The three common states of matter - solids, liquids, and gases - are described based on how tightly or loosely the particles are packed. Key concepts like the mole, molar mass, empirical and molecular formulas are also introduced. Measurement units commonly used in chemistry like grams, meters, and moles are defined according to the International System of Units.
Chemistry involves experimentally studying the physical and chemical properties of substances and measuring them precisely. Measurements have some uncertainty depending on the skill of the person and instrument used. Significant figures refer to the digits that convey the accuracy of a measurement based on the instrument's least count. Chemical quantities and reactions follow various laws including the law of conservation of mass, law of definite proportions, law of multiple proportions, and Gay-Lussac's law of gas volumes in chemical combinations. Dalton's atomic hypothesis provided a theoretical basis for these laws by proposing that elements are made of atoms that combine in fixed ratios to form compounds.
The document provides an overview of organic reactions, describing common reaction types like addition, elimination, substitution, and rearrangement. It explains that organic reactions can be described in terms of their mechanisms, which involve the making and breaking of covalent bonds. Polar reactions occur through the attack of electron-rich nucleophiles on electron-deficient electrophilic sites, while radical reactions proceed through the formation, reaction, and termination of free radicals. Curved arrows are used to indicate the flow of electrons between reagents in reaction mechanisms.
it describes the bony anatomy including the femoral head , acetabulum, labrum . also discusses the capsule , ligaments . muscle that act on the hip joint and the range of motion are outlined. factors affecting hip joint stability and weight transmission through the joint are summarized.
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Executive Directors Chat Leveraging AI for Diversity, Equity, and InclusionTechSoup
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This presentation was provided by Steph Pollock of The American Psychological Association’s Journals Program, and Damita Snow, of The American Society of Civil Engineers (ASCE), for the initial session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session One: 'Setting Expectations: a DEIA Primer,' was held June 6, 2024.
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This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
1. Class XII
Chapter 3 – Electrochemistry
Chemistry
Question 3.1:
Arrange the following metals in the order in which they displace each other from the
solution of their salts.
Al, Cu, Fe, Mg and Zn
Answer
The following is the order in which the given metals displace each other from the solution
of their salts.
Mg, Al, Zn, Fe, Cu
Question 3.2:
Given the standard electrode potentials,
K+/K = −2.93V, Ag+/Ag = 0.80V,
Hg2+/Hg = 0.79V
Mg2+/Mg = −2.37 V, Cr3+/Cr = − 0.74V
Arrange these metals in their increasing order of reducing power.
Answer
The lower the reduction potential, the higher is the reducing power. The given standard
electrode potentials increase in the order of K+/K < Mg2+/Mg < Cr3+/Cr < Hg2+/Hg <
Ag+/Ag.
Hence, the reducing power of the given metals increases in the following order:
Ag < Hg < Cr < Mg < K
Question 3.3:
Depict the galvanic cell in which the reaction Zn(s) + 2Ag+(aq) → Zn2+(aq) + 2Ag(s)
takes place. Further show:
(i) Which of the electrode is negatively charged?
(ii) The carriers of the current in the cell.
(iii) Individual reaction at each electrode.
Answer
The galvanic cell in which the given reaction takes place is depicted as:
(i) Zn electrode (anode) is negatively charged.
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2. Class XII
Chapter 3 – Electrochemistry
Chemistry
(ii) Ions are carriers of current in the cell and in the external circuit, current will flow
from silver to zinc.
(iii) The reaction taking place at the anode is given by,
The reaction taking place at the cathode is given by,
Question 3.4:
Calculate the standard cell potentials of galvanic cells in which the following reactions
take place:
(i) 2Cr(s) + 3Cd2+(aq) → 2Cr3+(aq) + 3Cd
(ii) Fe2+(aq) + Ag+(aq) → Fe3+(aq) + Ag(s)
Calculate the ∆rGθ and equilibrium constant of the reactions.
Answer
(i)
The galvanic cell of the given reaction is depicted as:
Now, the standard cell potential is
In the given equation,
n=6
F = 96487 C mol−1
= +0.34 V
Then,
= −6 × 96487 C mol−1 × 0.34 V
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3. Class XII
Chapter 3 – Electrochemistry
Chemistry
= −196833.48 CV mol−1
= −196833.48 J mol−1
= −196.83 kJ mol−1
Again,
= −RT ln K
= 34.496
K = antilog (34.496)
= 3.13 × 1034
(ii)
The galvanic cell of the given reaction is depicted as:
Now, the standard cell potential is
Here, n = 1.
Then,
= −1 × 96487 C mol−1 × 0.03 V
= −2894.61 J mol−1
= −2.89 kJ mol−1
Again,
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4. Class XII
Chapter 3 – Electrochemistry
Chemistry
= 0.5073
K = antilog (0.5073)
= 3.2 (approximately)
Question 3.5:
Write the Nernst equation and emf of the following cells at 298 K:
(i) Mg(s) | Mg2+(0.001M) || Cu2+(0.0001 M) | Cu(s)
(ii) Fe(s) | Fe2+(0.001M) || H+(1M)|H2(g)(1bar) | Pt(s)
(iii) Sn(s) | Sn2+(0.050 M) || H+(0.020 M) | H2(g) (1 bar) | Pt(s)
(iv) Pt(s) | Br2(l) | Br−(0.010 M) || H+(0.030 M) | H2(g) (1 bar) | Pt(s).
Answer
(i) For the given reaction, the Nernst equation can be given as:
= 2.7 − 0.02955
= 2.67 V (approximately)
(ii) For the given reaction, the Nernst equation can be given as:
= 0.52865 V
= 0.53 V (approximately)
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5. Class XII
Chapter 3 – Electrochemistry
Chemistry
(iii) For the given reaction, the Nernst equation can be given as:
= 0.14 − 0.0295 × log125
= 0.14 − 0.062
= 0.078 V
= 0.08 V (approximately)
(iv) For the given reaction, the Nernst equation can be given as:
Question 3.6:
In the button cells widely used in watches and other devices the following reaction takes
place:
Zn(s) + Ag2O(s) + H2O(l) → Zn2+(aq) + 2Ag(s) + 2OH−(aq)
Determine
and
for the reaction.
Answer
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6. Class XII
Chapter 3 – Electrochemistry
Chemistry
= 1.104 V
We know that,
= −2 × 96487 × 1.04
= −213043.296 J
= −213.04 kJ
Question 3.7:
Define conductivity and molar conductivity for the solution of an electrolyte. Discuss
their variation with concentration.
Answer
Conductivity of a solution is defined as the conductance of a solution of 1 cm in length
and area of cross-section 1 sq. cm. The inverse of resistivity is called conductivity or
specific conductance. It is represented by the symbolκ. If ρ is resistivity, then we can
write:
The conductivity of a solution at any given concentration is the conductance (G) of one
unit volume of solution kept between two platinum electrodes with the unit area of
cross-section and at a distance of unit length.
i.e.,
(Since a = 1, l = 1)
Conductivity always decreases with a decrease in concentration, both for weak and
strong electrolytes. This is because the number of ions per unit volume that carry the
current in a solution decreases with a decrease in concentration.
Molar conductivity:
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7. Class XII
Chapter 3 – Electrochemistry
Chemistry
Molar conductivity of a solution at a given concentration is the conductance of volume V
of a solution containing 1 mole of the electrolyte kept between two electrodes with the
area of cross-section A and distance of unit length.
Now, l = 1 and A = V (volume containing 1 mole of the electrolyte).
Molar conductivity increases with a decrease in concentration. This is because the total
volume V of the solution containing one mole of the electrolyte increases on dilution.
The variation of
with
for strong and weak electrolytes is shown in the following
plot:
Question 3.8:
The conductivity of 0.20 M solution of KCl at 298 K is 0.0248 Scm−1. Calculate its molar
conductivity.
Answer
Given,
κ = 0.0248 S cm−1
c = 0.20 M
Molar conductivity,
= 124 Scm2mol−1
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8. Class XII
Chapter 3 – Electrochemistry
Chemistry
Question 3.9:
The resistance of a conductivity cell containing 0.001M KCl solution at 298 K is 1500
.
What is the cell constant if conductivity of 0.001M KCl solution at 298 K is 0.146 × 10−3
S cm−1.
Answer
Given,
Conductivity, κ = 0.146 × 10−3 S cm−1
Resistance, R = 1500
Cell constant = κ × R
= 0.146 × 10−3 × 1500
= 0.219 cm−1
Question 3.10:
The conductivity of sodium chloride at 298 K has been determined at different
concentrations and the results are given below:
Concentration/M 0.001 0.010 0.020 0.050 0.100
102 × κ/S m−1 1.237 11.85 23.15 55.53 106.74
Calculate
of
for all concentrations and draw a plot between
and c½. Find the value
.
Answer
Given,
κ = 1.237 × 10−2 S m−1, c = 0.001 M
Then, κ = 1.237 × 10−4 S cm−1, c½ = 0.0316 M1/2
= 123.7 S cm2 mol−1
Given,
κ = 11.85 × 10−2 S m−1, c = 0.010M
Then, κ = 11.85 × 10−4 S cm−1, c½ = 0.1 M1/2
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9. Class XII
Chapter 3 – Electrochemistry
Chemistry
= 118.5 S cm2 mol−1
Given,
κ = 23.15 × 10−2 S m−1, c = 0.020 M
Then, κ = 23.15 × 10−4 S cm−1, c1/2 = 0.1414 M1/2
= 115.8 S cm2 mol−1
Given,
κ = 55.53 × 10−2 S m−1, c = 0.050 M
Then, κ = 55.53 × 10−4 S cm−1, c1/2 = 0.2236 M1/2
= 111.1 1 S cm2 mol−1
Given,
κ = 106.74 × 10−2 S m−1, c = 0.100 M
Then, κ = 106.74 × 10−4 S cm−1, c1/2 = 0.3162 M1/2
= 106.74 S cm2 mol−1
Now, we have the following data:
0.0316
0.1
0.1414
0.2236
0.3162
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10. Class XII
Chapter 3 – Electrochemistry
123.7
118.5
115.8
at 124.0 S cm2 mol−1,
Since the line interrupts
111.1
Chemistry
106.74
= 124.0 S cm2 mol−1.
Question 3.11:
Conductivity of 0.00241 M acetic acid is 7.896 × 10−5 S cm−1. Calculate its molar
conductivity and if
for acetic acid is 390.5 S cm2 mol−1, what is its dissociation
constant?
Answer
Given, κ = 7.896 × 10−5 S m−1
c = 0.00241 mol L−1
Then, molar conductivity,
= 32.76S cm2 mol−1
Again,
= 390.5 S cm2 mol−1
Now,
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11. Class XII
Chapter 3 – Electrochemistry
Chemistry
= 0.084
Dissociation constant,
= 1.86 × 10−5 mol L−1
Question 3.12:
How much charge is required for the following reductions:
(i) 1 mol of Al3+ to Al.
(ii) 1 mol of Cu2+ to Cu.
to Mn2+.
(iii) 1 mol of
Answer
(i)
Required charge = 3 F
= 3 × 96487 C
= 289461 C
(ii)
Required charge = 2 F
= 2 × 96487 C
= 192974 C
(iii)
i.e.,
Required charge = 5 F
= 5 × 96487 C
= 482435 C
Question 3.13:
How much electricity in terms of Faraday is required to produce
(i) 20.0 g of Ca from molten CaCl2.
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12. Class XII
Chapter 3 – Electrochemistry
Chemistry
(ii) 40.0 g of Al from molten Al2O3.
Answer
(i) According to the question,
Electricity required to produce 40 g of calcium = 2 F
Therefore, electricity required to produce 20 g of calcium
=1F
(ii) According to the question,
Electricity required to produce 27 g of Al = 3 F
Therefore, electricity required to produce 40 g of Al
= 4.44 F
Question 3.14:
How much electricity is required in coulomb for the oxidation of
(i) 1 mol of H2O to O2.
(ii) 1 mol of FeO to Fe2O3.
Answer
(i) According to the question,
Now, we can write:
Electricity required for the oxidation of 1 mol of H2O to O2 = 2 F
= 2 × 96487 C
= 192974 C
(ii) According to the question,
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13. Class XII
Chapter 3 – Electrochemistry
Chemistry
Electricity required for the oxidation of 1 mol of FeO to Fe2O3 = 1 F
= 96487 C
Question 3.15:
A solution of Ni(NO3)2 is electrolysed between platinum electrodes using a current of 5
amperes for 20 minutes. What mass of Ni is deposited at the cathode?
Answer
Given,
Current = 5A
Time = 20 × 60 = 1200 s
Charge = current × time
= 5 × 1200
= 6000 C
According to the reaction,
Nickel deposited by 2 × 96487 C = 58.71 g
Therefore, nickel deposited by 6000 C
= 1.825 g
Hence, 1.825 g of nickel will be deposited at the cathode.
Question 3.16:
Three electrolytic cells A,B,C containing solutions of ZnSO4, AgNO3 and CuSO4,
respectively are connected in series. A steady current of 1.5 amperes was passed
through them until 1.45 g of silver deposited at the cathode of cell B. How long did the
current flow? What mass of copper and zinc were deposited?
Answer
According to the reaction:
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14. Class XII
Chapter 3 – Electrochemistry
Chemistry
i.e., 108 g of Ag is deposited by 96487 C.
Therefore, 1.45 g of Ag is deposited by =
= 1295.43 C
Given,
Current = 1.5 A
Time
= 863.6 s
= 864 s
= 14.40 min
Again,
i.e., 2 × 96487 C of charge deposit = 63.5 g of Cu
Therefore, 1295.43 C of charge will deposit
= 0.426 g of Cu
i.e., 2 × 96487 C of charge deposit = 65.4 g of Zn
Therefore, 1295.43 C of charge will deposit
= 0.439 g of Zn
Question 3.17:
Using the standard electrode potentials given in Table 3.1, predict if the reaction
between the following is feasible:
(i) Fe3+(aq) and I−(aq)
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15. Class XII
Chapter 3 – Electrochemistry
Chemistry
(ii) Ag+ (aq) and Cu(s)
(iii) Fe3+ (aq) and Br− (aq)
(iv) Ag(s) and Fe3+ (aq)
(v) Br2 (aq) and Fe2+ (aq).
Answer
Since
for the overall reaction is positive, the reaction between Fe3+(aq) and I−(aq) is
feasible.
Since
for the overall reaction is positive, the reaction between Ag+
(aq)
and Cu(s) is
feasible.
Since
for the overall reaction is negative, the reaction between Fe3+(aq) and Br−(aq) is
not feasible.
Since
E for the overall reaction is negative, the reaction between Ag (s) and Fe3+(aq) is
not feasible.
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16. Class XII
Since
Chapter 3 – Electrochemistry
Chemistry
for the overall reaction is positive, the reaction between Br2(aq) and Fe2+(aq) is
feasible.
Question 3.18:
Predict the products of electrolysis in each of the following:
(i) An aqueous solution of AgNO3 with silver electrodes.
(ii) An aqueous solution of AgNO3with platinum electrodes.
(iii) A dilute solution of H2SO4with platinum electrodes.
(iv) An aqueous solution of CuCl2 with platinum electrodes.
Answer
(i) At cathode:
The following reduction reactions compete to take place at the cathode.
The reaction with a higher value of
takes place at the cathode. Therefore, deposition
of silver will take place at the cathode.
At anode:
The Ag anode is attacked by
ions. Therefore, the silver electrode at the anode
+
dissolves in the solution to form Ag .
(ii) At cathode:
The following reduction reactions compete to take place at the cathode.
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17. Class XII
Chapter 3 – Electrochemistry
The reaction with a higher value of
Chemistry
takes place at the cathode. Therefore, deposition
of silver will take place at the cathode.
At anode:
Since Pt electrodes are inert, the anode is not attacked by
ions. Therefore, OH− or
ions can be oxidized at the anode. But OH− ions having a lower discharge potential
and get preference and decompose to liberate O2.
(iii) At the cathode, the following reduction reaction occurs to produce H2 gas.
At the anode, the following processes are possible.
For dilute sulphuric acid, reaction (i) is preferred to produce O2 gas. But for concentrated
sulphuric acid, reaction (ii) occurs.
(iv) At cathode:
The following reduction reactions compete to take place at the cathode.
The reaction with a higher value of
takes place at the cathode. Therefore, deposition
of copper will take place at the cathode.
At
anode:
The following oxidation reactions are possible at the anode.
At the anode, the reaction with a lower value of
is preferred. But due to the over-
−
potential of oxygen, Cl gets oxidized at the anode to produce Cl2 gas.
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18. Class XII
Chapter 3 – Electrochemistry
Chemistry
Text solution
Question 3.1:
How would you determine the standard electrode potential of the systemMg2+ | Mg?
Answer
The standard electrode potential of Mg2+ | Mg can be measured with respect to the
standard hydrogen electrode, represented by Pt(s), H2(g) (1 atm) | H+(aq)(1 M).
A cell, consisting of Mg | MgSO4 (aq 1 M) as the anode and the standard hydrogen
electrode as the cathode, is set up.
Then, the emf of the cell is measured and this measured emf is the standard electrode
potential of the magnesium electrode.
Here,
for the standard hydrogen electrode is zero.
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19. Class XII
Chapter 3 – Electrochemistry
Chemistry
∴
Question 3.2:
Can you store copper sulphate solutions in a zinc pot?
Answer
Zinc is more reactive than copper. Therefore, zinc can displace copper from its salt
solution. If copper sulphate solution is stored in a zinc pot, then zinc will displace copper
from the copper sulphate solution.
Hence, copper sulphate solution cannot be stored in a zinc pot.
Question 3.3:
Consult the table of standard electrode potentials and suggest three substances that can
oxidise ferrous ions under suitable conditions.
Answer
Substances that are stronger oxidising agents than ferrous ions can oxidise ferrous ions.
;
This
implies
that
= −0.77 V
the
substances
having
higher
reduction
potentials
than
+0.77 V can oxidise ferrous ions to ferric ions. Three substances that can do so are F2,
Cl2, and O2.
Question 3.4:
Calculate the potential of hydrogen electrode in contact with a solution whose pH is 10.
Answer
For hydrogen electrode,
+
∴[H ] = 10
−10
, it is given that pH = 10
M
Now, using Nernst equation:
=
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20. Class XII
Chapter 3 – Electrochemistry
Chemistry
= −0.0591 log 1010
= −0.591 V
Question 3.5:
Calculate the emf of the cell in which the following reaction takes place:
Given that
= 1.05 V
Answer
Applying Nernst equation we have:
= 1.05 − 0.02955 log 4 × 104
= 1.05 − 0.02955 (log 10000 + log 4)
= 1.05 − 0.02955 (4 + 0.6021)
= 0.914 V
Question 3.6:
The cell in which the following reactions occurs:
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21. Class XII
has
Chapter 3 – Electrochemistry
Chemistry
= 0.236 V at 298 K.
Calculate the standard Gibbs energy and the equilibrium constant of the cell reaction.
Answer
Here, n = 2,
T = 298 K
We know that:
= −2 × 96487 × 0.236
= −45541.864 J mol−1
= −45.54 kJ mol−1
Again,
−2.303RT log Kc
= 7.981
∴Kc = Antilog (7.981)
= 9.57 × 107
Question 3.7:
Why does the conductivity of a solution decrease with dilution?
Answer
The conductivity of a solution is the conductance of ions present in a unit volume of the
solution. The number of ions (responsible for carrying current) decreases when the
solution is diluted. As a result, the conductivity of a solution decreases with dilution.
Question 3.8:
Suggest a way to determine the
value of water.
Answer
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22. Class XII
Chapter 3 – Electrochemistry
Applying Kohlrausch’s law of independent migration of ions, the
Chemistry
value of water can
be determined as follows:
Hence, by knowing the
values of HCl, NaOH, and NaCl, the
value of water can be
determined.
Question 3.9:
The molar conductivity of 0.025 mol L−1 methanoic acid is
46.1 S cm2 mol−1.
Calculate its degree of dissociation and dissociation constant. Given λ °(H+)
= 349.6 S cm2 mol−1 and λ °(HCOO−) = 54.6 S cm2 mol
Answer
C = 0.025 mol L−1
Now, degree of dissociation:
Thus, dissociation constant:
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23. Class XII
Chapter 3 – Electrochemistry
Chemistry
Question 3.10:
If a current of 0.5 ampere flows through a metallic wire for 2 hours, then how many
electrons would flow through the wire?
Answer
I = 0.5 A
t = 2 hours = 2 × 60 × 60 s = 7200 s
Thus, Q = It
= 0.5 A × 7200 s
= 3600 C
We know that
number of electrons.
Then,
Hence,
number of electrons will flow through the wire.
Question 3.11:
Suggest a list of metals that are extracted electrolytically.
Answer
Metals that are on the top of the reactivity series such as sodium, potassium, calcium,
lithium, magnesium, aluminium are extracted electrolytically.
Question 3.12:
What is the quantity of electricity in coulombs needed to reduce 1 mol of
? Consider the reaction:
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24. Class XII
Chapter 3 – Electrochemistry
Chemistry
Answer
The given reaction is as follows:
Therefore, to reduce 1 mole of
, the required quantity of electricity will be:
=6 F
= 6 × 96487 C
= 578922 C
Question 3.14:
Suggest two materials other than hydrogen that can be used as fuels in fuel cells.
Answer
Methane and methanol can be used as fuels in fuel cells.
Question 3.15:
Explain how rusting of iron is envisaged as setting up of an electrochemical cell.
Answer
In the process of corrosion, due to the presence of air and moisture, oxidation takes
place at a particular spot of an object made of iron. That spot behaves as the anode. The
reaction at the anode is given by,
Electrons released at the anodic spot move through the metallic object and go to another
spot of the object.
There, in the presence of H+ ions, the electrons reduce oxygen. This spot behaves as the
cathode. These H+ ions come either from H2CO3, which are formed due to the dissolution
of carbon dioxide from air into water or from the dissolution of other acidic oxides from
the atmosphere in water.
The reaction corresponding at the cathode is given by,
The overall reaction is:
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25. Class XII
Chapter 3 – Electrochemistry
Chemistry
Also, ferrous ions are further oxidized by atmospheric oxygen to ferric ions. These ferric
ions combine with moisture, present in the surroundings, to form hydrated ferric oxide
i.e., rust.
Hence, the rusting of iron is envisaged as the setting up of an electrochemical cell.
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