This document defines and classifies colloids. Colloids have particle sizes between 1-1000 nm, which are larger than true solutions and smaller than suspensions. Colloids are classified based on the physical state of the dispersed and dispersion medium (solid-liquid, liquid-liquid, etc.), interaction between the phases (lyophobic or lyophilic), and particle type (multimolecular, macromolecular, associated). Common colloids include emulsions, gels, sols, and foams. Properties include the Tyndall effect, Brownian motion, and coagulation with electrolytes. Colloids find applications in products like rubber, soaps, and medicines.
Polarographic technique is applied for the qualitative or quantitative analysis of electroreducible or oxidisable elements or groups.
It is an electromechanical technique of analyzing solutions that measures the current flowing between two electrodes in the solution as well as the gradually increasing applied voltage to determine respectively the concentration of a solute and its nature.
The principle in polarography is that a gradually increasing negative potential (voltage) is applied between a polarisable and non-polarisable electrode and the corresponding current is recorded.
Polarisable electrode: Dropping Mercury electrode
Non-polarisable electrode: Saturated Calomel electrode
From the current-voltage curve (Sigmoid shape), qualitative and quantitative analysis can be performed. This technique is called as polarography, the instrument used is called as polarograph and the current-voltage curve recorded is called as polarogram
Definition
Application
Difference between molecular and Colloidal dispersion
Characteristics of dispersed phase
Classification of colloidal dispersion
Purification of colloidal dispersion
Polarographic technique is applied for the qualitative or quantitative analysis of electroreducible or oxidisable elements or groups.
It is an electromechanical technique of analyzing solutions that measures the current flowing between two electrodes in the solution as well as the gradually increasing applied voltage to determine respectively the concentration of a solute and its nature.
The principle in polarography is that a gradually increasing negative potential (voltage) is applied between a polarisable and non-polarisable electrode and the corresponding current is recorded.
Polarisable electrode: Dropping Mercury electrode
Non-polarisable electrode: Saturated Calomel electrode
From the current-voltage curve (Sigmoid shape), qualitative and quantitative analysis can be performed. This technique is called as polarography, the instrument used is called as polarograph and the current-voltage curve recorded is called as polarogram
Definition
Application
Difference between molecular and Colloidal dispersion
Characteristics of dispersed phase
Classification of colloidal dispersion
Purification of colloidal dispersion
Intermediate state of mesophases & halfway between isotropic liquid &solid crystal.
In solid crystal, basic unit display translational long range order, with center of molecule located on crystal lattice &display orientational order.
In isotropic liquid, basic unit do not preset positional or orientational long rang order.
Classification of dispersed systems & their general characteristics, size & shapes of colloidal particles, classification of colloids & comparative account of their general properties. Optical, kinetic & electrical properties. Effect of electrolytes, coacervation, peptization& protective action.
State of matter and properties of matter (Part-2) (Latent Heat, Vapour pressu...Ms. Pooja Bhandare
Latent Heat, Vapour pressure, Factor affecting vapour pressure, Surface area, Types of molecule, Temperature and Intermolecular forces, Sublimation Critical point
content- Principle
Ilkovic equation
Construction and working of dropping mercury electrode and rotating platinum electrode
Applications
Polarography is a voltammetric technique in which chemical species (ions or molecules) undergo oxidation (lose electrons) or reduction (gain electrons) at the surface of a dropping mercury electrode (DME) at an applied potential. Polarography only applies to the DME.
Objective of polarography
Polarography is an electroanalytical technique that measures the current flowing between two electrodes in the solution (in the presence of gradually increasing applied voltage) to determine the concentration of solute and its nature respectively
Polarography is based upon the principle that gradually increasing voltage is applied between two electrodes, one of which is polarisable (dropping mercury electrode) and other is non-polarisable and current flowing between the two electrodes is recorded.
A sigmoid shape current-voltage curve is obtained from which half wave potential as well as diffusion current is calculated.
Diffusion current is used for determination of concentration of substance.
Half wave potential is characteristic of every element.
Ilkovic equation is a relation used in polarography relating the diffusion current (id) and the concentration of the non-polarisable electrode, i.e., the substance reduced or oxidised at the dropping mercury electrode (polarisable electrode).
Definitions of types of currents
1. Residual current (ir), 2. Migration current (im): , 3. Diffusion current (id) 4.Half wave potential 5. Limiting current (il)
Dropping mercury electrode- Dropping mercury electrode (DME) is a polarisable electrode and can act as both anode and cathode.
The pool of mercury acts as counter electrode,
i.e., anode if DME is cathode or
cathode if DME is anode.
The counter electrode is a non-polarisable electrode.
To the analyte solution, electrolyte like KCl is added i.e., 50-100 times of sample concentration.
Pure nitrogen or hydrogen gas is bubbled through the solution, to expel (remove) out oxygen.
Eg: If the analyte solution contains cadmium ions, then cadmium ions are discharged at cathode (-)
Cd2+ + 2e- → Cd
Then, gradually increasing voltage is applied to the polarographic cell and current is recorded.
Graph is plotted between voltage applied and current. This graph is called Polarograph and the apparatus is known as Polarogram.
The diffusion current produced is directly proportional to concentration of analyte and this is used in quantitative analysis.
The half wave potential is characteristic of every compound and this is used in qualitative analysis.
Graph is plotted between voltage applied and current. This graph is called Polarograph and the apparatus is known as Polarogram.
The diffusion current produced is directly proportional to concentration of analyte and this is used in quantitative analysis.
The half wave potential is characteristic of every compound
It is an electrochemical method of analysis used for the determination or measurement of the electrical conductance of an electrolyte solution by means of a conductometer.
Electric conductivity of an electrolyte solution depends on :
Type of ions (cations, anions, singly or doubly charged
Concentration of ions
Temperature
Mobility of ions
The main principle involved in this method is that the movement of the ions creates the electrical conductivity. The movement of the ions is mainly depended on the concentration of the ions.
The electric conductance in accordance with ohms law which states that the strength of current (i) passing through conductor is directly proportional to potential difference & inversely to resistance.
i =V/R
Intermediate state of mesophases & halfway between isotropic liquid &solid crystal.
In solid crystal, basic unit display translational long range order, with center of molecule located on crystal lattice &display orientational order.
In isotropic liquid, basic unit do not preset positional or orientational long rang order.
Classification of dispersed systems & their general characteristics, size & shapes of colloidal particles, classification of colloids & comparative account of their general properties. Optical, kinetic & electrical properties. Effect of electrolytes, coacervation, peptization& protective action.
State of matter and properties of matter (Part-2) (Latent Heat, Vapour pressu...Ms. Pooja Bhandare
Latent Heat, Vapour pressure, Factor affecting vapour pressure, Surface area, Types of molecule, Temperature and Intermolecular forces, Sublimation Critical point
content- Principle
Ilkovic equation
Construction and working of dropping mercury electrode and rotating platinum electrode
Applications
Polarography is a voltammetric technique in which chemical species (ions or molecules) undergo oxidation (lose electrons) or reduction (gain electrons) at the surface of a dropping mercury electrode (DME) at an applied potential. Polarography only applies to the DME.
Objective of polarography
Polarography is an electroanalytical technique that measures the current flowing between two electrodes in the solution (in the presence of gradually increasing applied voltage) to determine the concentration of solute and its nature respectively
Polarography is based upon the principle that gradually increasing voltage is applied between two electrodes, one of which is polarisable (dropping mercury electrode) and other is non-polarisable and current flowing between the two electrodes is recorded.
A sigmoid shape current-voltage curve is obtained from which half wave potential as well as diffusion current is calculated.
Diffusion current is used for determination of concentration of substance.
Half wave potential is characteristic of every element.
Ilkovic equation is a relation used in polarography relating the diffusion current (id) and the concentration of the non-polarisable electrode, i.e., the substance reduced or oxidised at the dropping mercury electrode (polarisable electrode).
Definitions of types of currents
1. Residual current (ir), 2. Migration current (im): , 3. Diffusion current (id) 4.Half wave potential 5. Limiting current (il)
Dropping mercury electrode- Dropping mercury electrode (DME) is a polarisable electrode and can act as both anode and cathode.
The pool of mercury acts as counter electrode,
i.e., anode if DME is cathode or
cathode if DME is anode.
The counter electrode is a non-polarisable electrode.
To the analyte solution, electrolyte like KCl is added i.e., 50-100 times of sample concentration.
Pure nitrogen or hydrogen gas is bubbled through the solution, to expel (remove) out oxygen.
Eg: If the analyte solution contains cadmium ions, then cadmium ions are discharged at cathode (-)
Cd2+ + 2e- → Cd
Then, gradually increasing voltage is applied to the polarographic cell and current is recorded.
Graph is plotted between voltage applied and current. This graph is called Polarograph and the apparatus is known as Polarogram.
The diffusion current produced is directly proportional to concentration of analyte and this is used in quantitative analysis.
The half wave potential is characteristic of every compound and this is used in qualitative analysis.
Graph is plotted between voltage applied and current. This graph is called Polarograph and the apparatus is known as Polarogram.
The diffusion current produced is directly proportional to concentration of analyte and this is used in quantitative analysis.
The half wave potential is characteristic of every compound
It is an electrochemical method of analysis used for the determination or measurement of the electrical conductance of an electrolyte solution by means of a conductometer.
Electric conductivity of an electrolyte solution depends on :
Type of ions (cations, anions, singly or doubly charged
Concentration of ions
Temperature
Mobility of ions
The main principle involved in this method is that the movement of the ions creates the electrical conductivity. The movement of the ions is mainly depended on the concentration of the ions.
The electric conductance in accordance with ohms law which states that the strength of current (i) passing through conductor is directly proportional to potential difference & inversely to resistance.
i =V/R
Colloids are crucial to both ordinary living and pharmacological formulations. the study of both big molecules
and intricately divided multiphase systems is known as colloidal science. the intersection of colloid and
surface science is the multi-phase system. a colloid is a mixture in which one material is suspended within
another substance and has insoluble particles scattered over a tiny scale. between genuine solutions and
suspensions, colloidal solutions or colloidal dispersions represent a middle ground. the dispersed phase of
colloids is distributed throughout the dispersion medium. in many facets of chemistry, colloidal chemistry
knowledge is necessary. this article provides information on what colloids are, their types, sizes, forms,
qualities, and uses.
Here almost full every topics interrelated with colloid chemistry has been discussed.The slides have been made showing question pattern taking Begum Rokeya University Chemistry Department previous year questions to appear the slides easy towards the viewers.Stay join with me.Thank you.
A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others extend the definition to include substances like aerosols and gels.
covering also physiological properties of colloids
you can dowenload the interactive powerpoint through this link:
https://docs.google.com/presentation/d/1FXeeOruLdn26OxSferhl_2-sadnpmuhd/edit?usp=share_link&ouid=107152891770522030883&rtpof=true&sd=true
Soft matter or soft condensed matter is a subfield of condensed matter comprising a variety of physical systems that are deformed or structurally altered by thermal or mechanical stress of the magnitude of thermal fluctuations. They include liquids, colloids, polymers, foams, gels, granular materials, liquid crystals, and a number of biological materials. These materials share an important common feature in that predominant physical behaviors occur at an energy scale comparable with room temperature thermal energy. At these temperatures, quantum aspects are generally unimportant. Pierre-Gilles de Gennes, who has been called the "founding father of soft matter,"[1] received the Nobel Prize in physics in 1991 for discovering that methods developed for studying order phenomena in simple systems can be generalized to the more complex cases found in soft matter, in particular, to the behaviors of liquid crystals and polymers.[2]
Contents
1 Distinctive physics
2 Applications
3 Research
4 Related
5 See also
6 References
7 External links
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
ANAMOLOUS SECONDARY GROWTH IN DICOT ROOTS.pptxRASHMI M G
Abnormal or anomalous secondary growth in plants. It defines secondary growth as an increase in plant girth due to vascular cambium or cork cambium. Anomalous secondary growth does not follow the normal pattern of a single vascular cambium producing xylem internally and phloem externally.
Toxic effects of heavy metals : Lead and Arsenicsanjana502982
Heavy metals are naturally occuring metallic chemical elements that have relatively high density, and are toxic at even low concentrations. All toxic metals are termed as heavy metals irrespective of their atomic mass and density, eg. arsenic, lead, mercury, cadmium, thallium, chromium, etc.
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.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
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.
Travis Hills' Endeavors in Minnesota: Fostering Environmental and Economic Pr...Travis Hills MN
Travis Hills of Minnesota developed a method to convert waste into high-value dry fertilizer, significantly enriching soil quality. By providing farmers with a valuable resource derived from waste, Travis Hills helps enhance farm profitability while promoting environmental stewardship. Travis Hills' sustainable practices lead to cost savings and increased revenue for farmers by improving resource efficiency and reducing waste.
Unveiling the Energy Potential of Marshmallow Deposits.pdf
Colloids and surface chemistry
1. Colloids
Solute and solvent are replaced by dispersed
phase & dispersion medium
Sols( solid in liquid),gels(liquids in solids),
emulsions (liquid in liquid)
Size of particles lies between that of true
solution and suspension, i.e. 10 Ao
to 1000 Ao
2. Property True solution Suspension Colloidal solution
Nature Heterogeneous Appears to be homogenous
but actually heterogeneous
Particle size < 10–9
Ao
(1 nm) > 1000 Ao
(100 nm) Between 10 Ao
(1 nm) to
1000 Ao
(100 nm)
Sedimentation Do not settle Settle on standing Do not settle
Diffusion Diffuse quickly Unable to diffuse Diffuse slowly
Visibility Particles invisible Particles visible by
naked eye or under
microscope
Particles scatter light and
can be observed under
ultramicroscope
Filterability Pass easily through
animal membrane
and filter paper
Unable to pass
through animal
membrane or filter
paper
Pass through filter paper
but not through animal
membrane
Appearance Clear and
transparent
Opaque Translucent
Homogeneous
3. Classification of colloids
Classification is based on following criteria
Physical state of dispersed phase and dispersion medium.
Nature of interaction between dispersed phase and dispersion medium.
Types of particles of the dispersed phase.
4. Classification based on physical state of
dispersed phase and dispersion medium
Eight types of colloidal systems are possible.
Dispersed
phase
Dispersion
medium
Type of
colloid
Example
Solid Solid Solid sol Some coloured glasses, and
gem stones
Solid Liquid Sol Paints, cell fluids
Solid Gas Aerosol Smoke, dust
Liquid Solid Gel Cheese butter, jellies
Liquid Liquid Emulsion Milk, hair cream
Liquid Gas Aerosol Fog, mist, cloud, insecticide
sprays
Gas Solid Solid sol Pumice stone, foam rubber
Gas Liquid Foam Froth, whipped cream, soap-
lather
5. Classification based on nature of interaction
Lyophobic colloids (solvent hating colloids )
When metals and their sulphides simply mixed with
dispersion medium, they don’t form colloids.
• need stabilizing to preserve them.
• irreversible.
• For example, colloidal solutions of gold,silver, Fe(OH)3
, As2
S3
, etc.
Lyophilic colloids ( solvent loving)
Directly formed by substances like gum, gelatine rubber etc.
on mixing with a suitable liquid(the dispersion medium).
• self-stabilizing
• reversible sols
• For example, gums, gelatin, starch, albumin in water.
6. Classification based on type of particles
of the dispersed phase
Multimolecular colloids : Consists of
aggregates of a large number of atoms
or smaller molecules whose diameter is
less than 1 nm
Macromolecular colloids: In these colloids,
the molecules have sizes and dimensions
comparable to colloidal particles. For example,
proteins, starch, cellulose.
7. Associated colloids
At low concentrations, behave as normal, strong electrolytes
At higher concentrations exhibit colloidal state properties due
to the formation of aggregated particles (micelles)
The formation of micelles takes place only
above a particular temperature called
Kraft temperature (Tk) and above a
particular micelle concentration called
Critical Micelle Concentration
E.g Soaps and detergents
8. Multimolecular colloids Macromolecular colloids Associated colloids
Formed by aggregation of
large number of atoms or
molecules with diameters
less than 1 nm
Formed by aggregation of large
number of ions in concentrated
solution
Lyophilic in nature Lyophobic in nature Both lyophilic and lyophobic in
nature
Molecular mass is
intermediate
High molecular mass High molecular mass
Held by weak van der
Waals’ forces
Held by stronger van der
Waals’ forces due to the
long chains
van der Waals’ forces increase
with increase in concentration
Formed by large
sized molecules
9. Preparation of Lyophobic sols
Condensation methods
Particles of atomic or molecular size are induced to form aggregates
Exchange of solvent
Colloidal solution of phosphorus is prepared by addition of alcohol
into a solution of phosphorous in excess water.
Oxidation method
Sulphur colloids are prepared by oxidation of H2S by O2.
Reduction
Silver colloids are prepared by passing H2 through a saturated aqueous
solution of silver oxide at 65° C.
Hydrolysis
Dark brown Fe(OH)3 colloidal solution is prepared by adding FeCl3
into boiling water.
Double decomposition
Arsenious sulphide colloidal solution is prepared by passing of
H2S gas into a solution of As2O3.
10. Preparation of Lyophobic sols
Dispersion methods
Mechanical disintegration
By vigorous mechanical agitation.
Peptization : Process of passing of a precipitate into colloidal particles
on adding suitable electrolyte is known as peptisation
e.g. Fe(OH)3 solution is formed from FeCl3.
Electrol-disintegration (Bredig’s arc method)
Electrical disintegration of a colloidal solution, e.g. alternating
current passed through a gold solution.
11. Purification of colloids
Ultrafiltration
In this process the colloidal particles are separated by the process of
filtration, through a filter paper, which is impregnated with gelatin or
collodion followed by hardening in formaldehyde.
Dialysis
In this process, the colloidal particles are separated from the
impurities (mainly electrolytes) by the diffusion through a porous
membrane such as parchment, collodion, etc.
Electrodialysis
This is a special type of dialysis process, which is accelerated by the
application of a potential difference across the membrane. So ions
migrate faster than the colloids .
12. Properties of colloids
Optical properties: Tyndall effect
When a beam of light falls at right angles to the line of view
through a solution, the solution appears to be luminescent and
due to scattering of light the path becomes visible.
Quite strong in lyophobic colloids while in lyophilic colloids it is quite weak.
15. Properties of colloids
Electro-osmosis: molecules of dispersion medium are allowed to move
under influence of electric field
Coagulation or flocculation:Process which involves coming
together of colloidal particles so as to change into large sized
particles which ultimately settle as a precipitate or float on
surface.It is generally brought about by addition of electrolytes.
The minimum amount of an electrolyte that must be added to one litre
of a colloidal solution so as to bring about complete coagulation or
flocculation is called coagulation or flocculation value.Smaller is the
flocculation value of an electrolyte,greater is the coagulating or
precipitating power.
16. Properties of colloids
For positively charged, then the coagulating
power of electrolytes follow the following order:
3 2
4 4PO SO Cl− − −
> >
Hardy schulze law : Coagulating power of an
electrolyte increases rapidly with the increase in
the valency of cation or anion.
For negatively charged sol, the coagulating
power of electrolytes are
AlCl3 > BaCl2 > NaCl or Al3+
> Ba2+
> Na+
17. Gold Number
Covering up of lyophobic particles by lyophilic
particles is known as its protective action and such
colloids are called protective colloids.
Gold number is defined as amount of protective sol
that will prevent the coagulation of 10 ml of a gold
solution on the addition of 1 ml of 10% NaCl solution.
Smaller the gold number,higher is protective power
18. Emulsion
A colloidal dispersion of one liquid in another
immiscible liquid is known as an emulsion,
e.g. milk, Na-soaps, vanishing cream, etc.
1. Oil in water, where oil is the dispersed phase and water
is the dispersion medium, e.g. milk.
2. Water in oil where water is the dispersed phase and oil
is the dispersed medium, e.g. butter, cream.
Types of emulsions
19. Cleaning Action of Soap
Soap contains a nonpolar carbon end that
dissolves in nonpolar fats and oils, and a
polar end that dissolves in water.
Dust and soap molecules form micelles
that dissolve in water and are
washed away.
Soap forms a precipitate with ions in hard
water (Ca2+
, Mg2+
, Fe3+
)
20. Applications of colloids
1. Rubber plating
2. Sewage disposal
3. Smoke screen
4. Purification of water
5. Cleaning action of soap
6. In medicine
7. Formation of delta
8. Photography
9. Artificial rain