Thermodynamics is the study of energy and its transformations. Thermochemistry is the subdiscipline involving chemical reactions and energy changes. The first law of thermodynamics states that energy is conserved as it transforms between forms. Energy exists in kinetic and potential forms. Kinetic energy is associated with motion, while potential energy is stored energy due to position or composition. Heat is the transfer of kinetic energy between objects of different temperatures until they reach equilibrium. Exothermic processes release heat from a system, while endothermic processes absorb heat into a system. Enthalpy changes (ΔH) quantify the heat absorbed or released by chemical reactions. Spontaneous processes are those that proceed without outside intervention, as dictated by a negative change
Lecture materials for the Introductory Chemistry course for Forensic Scientists, University of Lincoln, UK. See http://forensicchemistry.lincoln.ac.uk/ for more details.
Lecture materials for the Introductory Chemistry course for Forensic Scientists, University of Lincoln, UK. See http://forensicchemistry.lincoln.ac.uk/ for more details.
What constitutes waste depends on the eye of the beholder; one person's waste can be a resource for another person.[1] Though waste is a physical object, its generation is a physical and psychological process.[1] The definitions used by various agencies are as below.
United Nations Environment Program
According to the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal of 1989, Art. 2(1), "'Wastes' are substance or objects, which are disposed of or are intended to be disposed of or are required to be disposed of by the provisions of national law".[2]
United Nations Statistics Division
The UNSD Glossary of Environment Statistics[3] describes waste as "materials that are not prime products (that is, products produced for the market) for which the generator has no further use in terms of his/her own purposes of production, transformation or consumption, and of which he/she wants to dispose. Wastes may be generated during the extraction of raw materials, the processing of raw materials into intermediate and final products, the consumption of final products, and other human activities. Residuals recycled or reused at the place of generation are excluded."
European Union
Under the Waste Framework Directive 2008/98/EC, Art. 3(1), the European Union defines waste as "an object the holder discards, intends to discard or is required to discard."[4] For a more structural description of the Waste Directive, see the European Commission's summary.
Types of Waste
Municipal Waste
The Organization for Economic Co-operation and Development also known as OECD defines municipal solid waste (MSW) as “waste collected and treated by or for municipalities”. [5] Typically this type of waste includes household waste, commercial waste, and demolition or construction waste. In 2018, the Environmental Protection Agency concluded that 292.4 tons of municipal waste was generated which equated to about 4.9 pounds per day per person. Out of the 292.4 tons, approximately 69 million tons were recycled, and 25 million tons were composted. [6]
Household Waste and Commercial Waste
Household waste more commonly known as trash or garbage are items that are typically thrown away daily from ordinary households. Items often included in this category include product packaging, yard waste, clothing, food scraps, appliance, paints, and batteries.[7] Most of the items that are collected by municipalities end up in landfills across the world. In the United States, it is estimated that 11.3 million tons of textile waste is generated. On an individual level, it is estimated that the average American throws away 81.5 pounds of clothes each year.[8] As online shopping becomes more prevalent, items such as cardboard, bubble wrap, shipping envelopes are ending up in landfills across the United States. The EPA has estimated that approximately 10.1 million tons of plastic containers and packaging ended up landfills in 2018. The EPA noted that only 30.
Honour Chemistry Unit 4: Thermochemistry and Nuclear Chemistry
Copyrighted by Gabriel Tang B.Ed., B.Sc. Page 135.
Unit 4: THERMOCHEMISTRY AND NUCLEAR CHEMISTRY
Chapter 6: Thermochemistry
6.1: The Nature of Energy and Types of Energy
Energy (E): - the ability to do work or produce heat.
Different Types of Energy:
1. Radiant Energy: - solar energy from the sun.
2. Thermal Energy: - energy associated with the random motion of atoms and molecules.
3. Chemical Energy: - sometimes refer to as Chemical Potential Energy. It is the energy stored in the
chemical bonds, and release during chemical change.
4. Potential Energy: - energy of an object due to its position.
First Law of Thermodynamics: - states that energy cannot be created or destroyed. It can only be
converted from one form to another. Therefore, energy in the universe is
a constant.
- also known as the Law of Conservation of Energy (ΣEinitial = ΣEfinal).
6.2: Energy Changes in Chemical Reactions
Heat (q): - the transfer of energy between two objects (internal versus surroundings) due to the difference
in temperature.
Work (w): - when force is applied over a displacement in the same direction (w = F × d).
- work performed can be equated to energy if no heat is produced (E = w). This is known as the
Work Energy Theorem.
System: - a part of the entire universe as defined by the problem.
Surrounding: - the part of the universe outside the defined system.
Open System: - a system where mass and energy can interchange freely with its surrounding.
Closed System: - a system where only energy can interchange freely with its surrounding but mass not
allowed to enter or escaped the system.
Isolated System: - a system mass and energy cannot interchange freely with its surrounding.
Unit 4: Thermochemistry and Nuclear Chemistry Honour Chemistry
Page 136. Copyrighted by Gabriel Tang B.Ed., B.Sc.
Exothermic Process (ΔE < 0): - when energy flows “out” of the system into the surrounding.
(Surrounding gets Warmer.)
Endothermic Process (ΔE > 0): - when energy flows into the system from the surrounding.
(Surrounding gets Colder.)
6.3: Introduction of Thermodynamics
Thermodynamics: - the study of the inter action of heat and other kinds of energy.
State of a System: - the values of all relevant macroscopic properties like composition, energy,
temperature, pressure and volume.
State Function: - also refer to as State Property of a system at its present conditions.
- energy is a state function because of its independence of pathway, whereas work and heat
are not state properties.
Pathway: - the specific conditions that dictates ...
Need of thermodynamics and the Laws of Thermodynamics.
Important principles and definitions of thermochemistry.
Concept of standard state and standard enthalpies of formations,
Integral and differential enthalpies of solution and dilution.
Calculation of bond energy, bond dissociation energy and resonance energy from thermochemical data.
Variation of enthalpy of a reaction with temperature – Kirchhoff’s equation.
Statement of Third Law of thermodynamics and calculation of absolute entropies of substances.
JFI -just for information
What constitutes waste depends on the eye of the beholder; one person's waste can be a resource for another person.[1] Though waste is a physical object, its generation is a physical and psychological process.[1] The definitions used by various agencies are as below.
United Nations Environment Program
According to the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal of 1989, Art. 2(1), "'Wastes' are substance or objects, which are disposed of or are intended to be disposed of or are required to be disposed of by the provisions of national law".[2]
United Nations Statistics Division
The UNSD Glossary of Environment Statistics[3] describes waste as "materials that are not prime products (that is, products produced for the market) for which the generator has no further use in terms of his/her own purposes of production, transformation or consumption, and of which he/she wants to dispose. Wastes may be generated during the extraction of raw materials, the processing of raw materials into intermediate and final products, the consumption of final products, and other human activities. Residuals recycled or reused at the place of generation are excluded."
European Union
Under the Waste Framework Directive 2008/98/EC, Art. 3(1), the European Union defines waste as "an object the holder discards, intends to discard or is required to discard."[4] For a more structural description of the Waste Directive, see the European Commission's summary.
Types of Waste
Municipal Waste
The Organization for Economic Co-operation and Development also known as OECD defines municipal solid waste (MSW) as “waste collected and treated by or for municipalities”. [5] Typically this type of waste includes household waste, commercial waste, and demolition or construction waste. In 2018, the Environmental Protection Agency concluded that 292.4 tons of municipal waste was generated which equated to about 4.9 pounds per day per person. Out of the 292.4 tons, approximately 69 million tons were recycled, and 25 million tons were composted. [6]
Household Waste and Commercial Waste
Household waste more commonly known as trash or garbage are items that are typically thrown away daily from ordinary households. Items often included in this category include product packaging, yard waste, clothing, food scraps, appliance, paints, and batteries.[7] Most of the items that are collected by municipalities end up in landfills across the world. In the United States, it is estimated that 11.3 million tons of textile waste is generated. On an individual level, it is estimated that the average American throws away 81.5 pounds of clothes each year.[8] As online shopping becomes more prevalent, items such as cardboard, bubble wrap, shipping envelopes are ending up in landfills across the United States. The EPA has estimated that approximately 10.1 million tons of plastic containers and packaging ended up landfills in 2018. The EPA noted that only 30.
Honour Chemistry Unit 4: Thermochemistry and Nuclear Chemistry
Copyrighted by Gabriel Tang B.Ed., B.Sc. Page 135.
Unit 4: THERMOCHEMISTRY AND NUCLEAR CHEMISTRY
Chapter 6: Thermochemistry
6.1: The Nature of Energy and Types of Energy
Energy (E): - the ability to do work or produce heat.
Different Types of Energy:
1. Radiant Energy: - solar energy from the sun.
2. Thermal Energy: - energy associated with the random motion of atoms and molecules.
3. Chemical Energy: - sometimes refer to as Chemical Potential Energy. It is the energy stored in the
chemical bonds, and release during chemical change.
4. Potential Energy: - energy of an object due to its position.
First Law of Thermodynamics: - states that energy cannot be created or destroyed. It can only be
converted from one form to another. Therefore, energy in the universe is
a constant.
- also known as the Law of Conservation of Energy (ΣEinitial = ΣEfinal).
6.2: Energy Changes in Chemical Reactions
Heat (q): - the transfer of energy between two objects (internal versus surroundings) due to the difference
in temperature.
Work (w): - when force is applied over a displacement in the same direction (w = F × d).
- work performed can be equated to energy if no heat is produced (E = w). This is known as the
Work Energy Theorem.
System: - a part of the entire universe as defined by the problem.
Surrounding: - the part of the universe outside the defined system.
Open System: - a system where mass and energy can interchange freely with its surrounding.
Closed System: - a system where only energy can interchange freely with its surrounding but mass not
allowed to enter or escaped the system.
Isolated System: - a system mass and energy cannot interchange freely with its surrounding.
Unit 4: Thermochemistry and Nuclear Chemistry Honour Chemistry
Page 136. Copyrighted by Gabriel Tang B.Ed., B.Sc.
Exothermic Process (ΔE < 0): - when energy flows “out” of the system into the surrounding.
(Surrounding gets Warmer.)
Endothermic Process (ΔE > 0): - when energy flows into the system from the surrounding.
(Surrounding gets Colder.)
6.3: Introduction of Thermodynamics
Thermodynamics: - the study of the inter action of heat and other kinds of energy.
State of a System: - the values of all relevant macroscopic properties like composition, energy,
temperature, pressure and volume.
State Function: - also refer to as State Property of a system at its present conditions.
- energy is a state function because of its independence of pathway, whereas work and heat
are not state properties.
Pathway: - the specific conditions that dictates ...
Need of thermodynamics and the Laws of Thermodynamics.
Important principles and definitions of thermochemistry.
Concept of standard state and standard enthalpies of formations,
Integral and differential enthalpies of solution and dilution.
Calculation of bond energy, bond dissociation energy and resonance energy from thermochemical data.
Variation of enthalpy of a reaction with temperature – Kirchhoff’s equation.
Statement of Third Law of thermodynamics and calculation of absolute entropies of substances.
JFI -just for information
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
2. Thermodynamics: the study of energy and
its transformations
Thermochemistry: the sub discipline involving
chemical reactions and
energy changes
3. Energy
•Energy is defined as the capacity to do work or to produce
heat.
•The 1st Law of Thermodynamics …. Energy is conserved
as it is converted between one form and another, it will be
neither created or destroyed, but simply change form…thus
making the energy of the universe constant!
•Energy can be classified as either Kinetic or Potential
4. Kinetic energy: energy associated with the motion of
atoms and molecules in a system.
KE = ½ mv2
Temperature is a measure of the average KE of a
collection of particles in a system.
RECALL…….
5. Heat vs Energy
•Thermal energy is the energy of the
object and is not in the process of being
transferred or moved.
•Heat is kinetic energy being transferred
–It moves from a hotter object towards cooler
object until the temperatures are the same.
–At this point the KE’s are at equilibrium.
–It is not a property of the substance.
6. System: the part of the universe we are
studying
Surroundings: everything else
Usually, energy is transferred to...
(1)
(2)
Change an object’s state of motion
like fuel in a vehicle.
Cause a temperature change like
a furnace warming a house.
In chemistry the system is the reaction that
we are interested in and the surroundings
could be the container that the reaction
takes place in.
7. Units of energy are
either
joules (J)
kilojoules (kJ)
CONVERSIONS:
Divide by 1000 to convert from J to KJ
Multiply by 1000 to convert from KJ to J
James
Prescott
Joule
(1818-1889)
4184 J = 4.184 kJ
8. In endothermic processes, heat is _________ by
the system.
absorbed
melting
boiling
sublimation
released
freezing
condensation
deposition
In exothermic processes, heat is ________ by
the system.
10. • Exothermic process is any process that gives off heat –
The energy will be listed as a product.
2H2 (g) + O2 (g) 2H2O (l) + energy
H2O (g) H2O (l) + energy
Endothermic process is any process in which heat is
required by the system. The energy is listed as a reactant.
energy + 2HgO (s) 2Hg (l) + O2 (g)
energy + H2O (s) H2O (l)
11.
12. ΔH = Hproducts – Hreactants
When ΔH is +, the system... has gained heat.
When ΔH is –, the system... has lost heat.
(ENDO)
(EXO)
Enthalpy is used to measure the heat that is
either gained or lost by a system that is at
constant pressure.
• Enthalpy is an extensive property, meaning that…the
amount of material affects its value
14. H2O (s) H2O (l) ΔH = 6.01 kJ/mol ΔH = 6.01 kJ
Thermochemical Equations
If you reverse a reaction, the sign of ΔH changes
H2O (l) H2O (s) ΔH =- 6.01 kJ
If you multiply both sides of the equation by a factor n,
then ΔH must change by the same factor n.
2H2O (s) 2H2O (l)
ΔH = 2 mol x 6.01 kJ/mol = 12.0 kJ
15. H2O (s) H2O (l) ΔH = 6.01KJ
The physical states of all reactants and products must be
specified in thermochemical equations.
Thermochemical Equations
H2O (l) H2O (g) ΔH = 44.0 KJ
Practice Question:
How much heat is evolved when 266 g of white
phosphorus (P4) burns in air? ΔHreaction = -3013 kJ
16. 2 H2(g) + O2(g) → 2 H2O(g) ΔH = – 483.6 kJ
What is the enthalpy change when 178 g of H2O(g)
are produced?
The space shuttle was powered
by the reaction above.
17. Calorimetry: the measurement of heat flow
A Calorimeter is used to measure the heat changes
molar heat (capacity): amt. of heat needed to raise
temp. of 1 mol of a substance
J/ C *mol or J/ K*mol
specific heat (capacity): amt. of heat needed to raise
temp. of 1 g of a substance
J/ C *g or J/ K*g
18. cX = heat of fusion (s/l)
or heat of vaporization (l/g)
We calculate the heat a substance loses or gains using:
q = heat
m = amount of substance
c = substance’s heat capacity
ΔT = temperature change
q = m c ΔT
(for within a given
state of matter)
AND q = m cX
(for between two states
of matter when temp is
constant)
19. Heat capacities of metals are very low when
compared to water or other substances.
20. In an experiment it was determined that 59.8 J was required to
change the temperature of 25.0 g of ethylene glycol (a compound
used as antifreeze in automobile engines) by 10.0 C.
Calculate the specific heat capacity of ethylene glycol.
q = m c ΔT
22. Constant Pressure Calorimetry
• Commonly called
“COFFEE CUP” calorimetry
• It’s used to determine any
changes in enthalpy for
reactions occurring in
solution.
• Atmospheric pressure
remains constant during the
reaction .
Calorimetry:
The measurement of heat flow
23. Practice Problem
A lead (Pb) pellet having a mass of 26.47 g at 89.98°C
was placed in a constant-pressure calorimeter
containing 100.0 mL of water. The water temperature
rose from 22.50°C to 23.17°C.
What is the specific heat of the lead pellet?
24. A sketch of the initial and final situation is as follows:
We know the masses of water and the lead pellet as well as the initial and final
temperatures. Assuming no heat is lost to the surroundings, we can equate the heat lost
by the lead pellet to the heat gained by the water. Knowing the specific heat of water,
we can then calculate the specific heat of lead.
25. Because the heat lost by the lead pellet is equal to the heat
gained by the water,
qPb = −280.3 J.
27. We assume that no energy escapes into the
surroundings, so that the heat absorbed by the bomb
calorimeter equals the heat given off by the reaction.
28. Hess’ Law 1840
•The change of enthalpy in a chemical
reaction is independent of the route by which
the chemical change occurs.
•This is true because enthalpy is a state
function , which is a value that does not
depend on the path taken
29. ● The ΔHrxns have been calculated and tabulated
for many basic reactions.
● Hess’s law allows us to put these simple
reactions together like puzzle piecesso that they
can add up to a more complicated reaction.
● By adding orsubtracting the ΔHrxns, we can
determine the ΔHrxn of the more complicated
reaction.
How Hess’s Law works
30. Hess's Law is saying:
If you convert reactants A into products B, the overall
enthalpy change will be exactly the same whether you do
it in one step or two steps or however many steps.
31. Important things to remember when using Hess’s Law:
● If a reaction is reversed, the sign of H is also reversed.
● The size of H is directly related to the quantities of
reactants and products
● If the coefficients in a balanced reaction are multiplied
by an integer, the value of H is multiplied by the same
integer.
32. Calculate the enthalpy for this reaction
2C(s) + H2(g) ---> C2H2(g) ΔH° = ??? kJ
Given the following thermochemical equations:
C2H2(g) + (5/2)O2(g) ---> 2CO2(g) + H2O(ℓ) ΔH° = -1299.5 kJ
C(s) + O2(g) ---> CO2(g) ΔH° = -393.5 kJ
H2(g) + (1/2)O2(g) ---> H2O(ℓ) ΔH° = -285.8 kJ
33. 1) Determine what must be done to the given equations to get the target equation:
a) first eq: flip it so as to put C2H2 on the product side
b) second eq: multiply it by two to get 2C
c) third eq: do nothing. We need one H2 on the reactant side and that's what we have.
2CO2(g) + H2O(ℓ) ---> C2H2(g) + (5/2)O2(g) ΔH° = +1299.5 kJ
2C(s) + 2O2(g) ---> 2CO2(g) ΔH° = -787.0 kJ
H2(g) + (1/2)O2(g) ---> H2O(ℓ) ΔH° = -285.8 kJ
Notice that the ΔH values changed as well
Add up ΔH values for our answer:
+1299.5 kJ + (-787 kJ) + (-285.8 kJ) = +226.7 kJ
34. Standard enthalpy of formation (ΔHf
0) is the heat change
that results when one mole of a compound is formed from
its elements at STP.
Whenever a standard enthalpy change is quoted, standard
conditions are assumed.
The standard enthalpy of formation of any element in its
most stable form is zero.
ΔHf
0 (O2) = 0
ΔH0 (O3) = 142kJ/mol
f
ΔHf
0 (C, graphite) = 0
ΔHf
0 (C, diamond) = 1.90 kJ/mol
35. Some other important types of
enthalpy changes
Standard enthalpy change of combustion, ΔH°c
The standard enthalpy change of combustion of a
compound is the enthalpy change which occurs
when one mole of the compound is burned
completely in oxygen at STP .
The enthalpy change of solution (ΔH soln) is the
heat generated or absorbed when a certain amount
of solute dissolves in a certain amount of solvent at
STP.
36. Standard enthalpy of a reaction (ΔHo
rxn):
Using Hess’s law, we can easily calculate
ΔHo
rxn from the ΔHf
o of all reactants and products by
using the following equation:
ΔHo
rxn = Σ (ΔH fproducts) – Σ (ΔH f reactants)
37. –238.6 kJ/mol
Approximate the enthalpy change for the
combustion of 246 g of liquid methanol.
CH3OH(l) O2(g) CO2(g) H2O(g)
+ +
2
X 2
2 4
–393.5 kJ/mol –241.8 kJ/mol
0 kJ/mol
X 2 X 4
–477.2 kJ –1754.2 kJ
ΔHo
rxn
=
(–1754.2 kJ) – (–477.2)
kJ)
= –1277 kJ
for 2 mol
(i.e., 64 g)
of CH3OH
So…
X = ΔH = –4910 kJ
3
(Look these up.
See App. 4,
P A19.)
38. Practice problem #1
Benzene (C6H6) burns in air to produce carbon dioxide and liquid
water. How much heat is released per mole of benzene
combusted?
The standard enthalpy of formation of benzene is 49.04 kJ/mol.
2C6H6 (l) + 15O2 (g) 12CO2 (g) + 6H2O (g)
39. Practice Problem # 2
What is the Δ Hrxn for the complete
combustion of Butane, C4H10 (g)?
2 C4H10 (g) + 13 O 2(g) 8CO2 (g) + 10 H2O (g)
41. Think of these commonplace
experiences:
● A Hot frying pans cool down when
taken off the stove.
● Air in a high-pressure tire shoots out
from even a small hole in its side to the
lower pressure atmosphere.
● Ice cubes melt in a warm room.
● Iron exposed to oxygen and water will
form rust.
42. What’s happening in each of those processes?
● Energy of some kind is changing from being localized,
concentrated, and contained to becoming more spread
out and dispersed.
● Entropy is the measurement of disorder of a system
and it is given the letter S, and it is temperature
dependent.
44. Ssolid < Sliquid < Sgas
• Entropy increases with dispersal of particles so,
entropies of gases are larger than liquids and liquid
entropies are larger than solids.
Entropies are greater for :
- more complex molecules
- Increased temperatures (KE)
- When volume increases for gases
+ΔS ………. Entropy increases
- ΔS ………. Entropy decreases
45. Which substance has the greater entropy?
CO2 (s) or CO2(g)
H2 (g) at 1 atm or H2 (g) at 1.0 x 10 -2 atm
What will the overall change in entropy?
● Solid sugar is added to water to make a sugar solution.
● Water vapor condenses.
● Ice melts
46. Entropy Changes in the System (ΔSsys)
When gases are produced (or consumed)
• If a reaction produces more gas molecules than it
consumes, ΔS0+
• If the total number of gas molecules diminishes, ΔS0-
What is the sign of the entropy change for the following
reaction?
2Zn (s) + O2 (g) 2ZnO (s)
The total number of gas molecules goes down….. ΔS0-
48. Chemical
Thermodynamics
Entropy on the Molecular Scale
Molecules exhibit several types of motion:
Translational: Movement of the entire molecule from
one place to another.
Vibrational: Periodic motion of atoms within a molecule.
Rotational: Rotation of the molecule on about an axis or
rotation about bonds.
49. Chemical
Thermodynamics
Entropy on the Molecular Scale
• Boltzmann envisioned the motions of a sample of
molecules at a particular instant in time.
This would be akin to taking a snapshot of all the
molecules.
• He referred to this sampling as a microstate of the
thermodynamic system.
50. Chemical
Thermodynamics
Entropy on the Molecular Scale
Implications:
• More Particles
-> more states -> more entropy
• Higher Temp
-> more energy states -> more entropy
• Less Structure (gas vs solid)
-> more states -> more entropy
51. The entropy change for a system(reaction) is calculated
from the entropies of the products and the reactants
ΔSo
system = Σ[So(products)] - Σ [So( reactants)]
ΔSo
system is Positive, then entropy increases
ΔSo
system is Negative,then entropy decreases
Calculations
53. Gibbs Free Energy
Gibbs Free Energy (G)
The energy associated with a chemical reaction
that can be used to do work.
54.
55. What are Spontaneous Processes ?
Spontaneous processes are
those that can proceed without
any outside intervention.
For example, the gas in vessel
B will spontaneously effuse
into vessel A, but once the
gas is in both vessels, it will
not spontaneously revert to
its original state.
57. For a constant-temperature process:
Gibbs free energy (G)
ΔG - The reaction is favorable (spontaneous) in the forward direction.
No outside energy is needed
Product formation is favored
ΔG + The reaction is unfavorable (non-spontaneous) as written.
The reaction is favorable (spontaneous) in the reverse direction
Reactant formation is favored
ΔG = 0 The reaction is at equilibrium and reactant and product
formation are equally favored
58. Recap: Signs of Thermodynamic Values
Negative Positive
Enthalpy (ΔH) Exothermic Endothermic
Entropy (ΔS) Less disorder More disorder
Gibbs Free Energy
(ΔG)
Favored Not favored
