This document provides an overview of various separation techniques and the kinetic particle theory. It discusses techniques like filtration, solubility, chromatography, crystallization, distillation and sublimation. It explains how each technique separates mixtures based on differences in properties like particle size, polarity, boiling point. It also summarizes the kinetic particle theory, stating that matter is made of particles in constant random motion and the states of matter can be understood by how closely packed and energetic the particles are.

1. Chemistry Notes
Overview
● Separation Techniques
● Kinetic Particle Theory
Separation Techniques
→ Filtration
● Based on the difference in particle size
● Mechanical or physical operation which is used for the separation of solids from fluids
(liquids or gases) by interposing a medium through which only the fluid can pass.
● Used to separate particles and fluid in a suspension
→ Solubility: The mass of solute that can dissolve in a fixed mass or volume of solvent at a
fixed temperature.
→ Chromatography
● Stationary phase is the silica gel/alumina which is polar. 2 compounds/elements (but
normally its compound) that are mixed together need to be different coloured and have
rather different polarity. Also normally solid + solid.
● Must dissolve the mixture in the mobile phase because it has to be in a liquid form to
pass through the super fine sieve stationary phase.
● First collect the mobile phase that is already in the column before the adding of the
mixture. (This was used to open pathways through the stationary phase for the mixture
to flow down.
● One that is more polar will stick/adhere to the column which is polar.
● The other which is less polar will travel more quickly through the column.
● The stationary phase is to slow the two substances down.
● When the first coloured substance (from mixture) flows down the the base of the
cotton wool (identified through colour), collect it. This is the separated substance from
the mixture dissolved in the mobile phase.

2. ● When the second coloured substance (from mixture) flows down the base of the cotton
(identified through colour), collect it. This is the separated substance from the mixture
dissolved in mobile phase.
● To get it back into solid form, evaporate the mobile phase.
→ Crystallisation
● based on the principles of solubility: compounds (solutes) tend to be more soluble in
hot liquids (solvents) than they are in cold liquids
● If a saturated hot solution is allowed to cool, the solute is no longer soluble in the
solvent and forms crystals of pure compound
→ Simple and fractional distillation
● The more volatile liquid (the liquid with the lower boiling point) will typically evaporate
first and the vapor will pass into a condensing column, where it can revert into a liquid
(condense) on the cool glass where it trickles into a collection flask.
● Heating further will cause the less volatile liquids to evaporate and distill at higher
temperatures.
● Fractional distillation is essentially the same as simple distillation except that a
fractionating column is placed between the boiling flask and the condenser. The
fractionating column is usually filled with glass or plastic beads. These beads improve
the separation between the liquids being distilled.
● The more volatile liquids will tend to push towards the top of the fractionating column,
while lower boiling liquids will stay towards the bottom, giving a better separation
between the liquids.
● Simple distillation is based on the lower boiling point of the solvent compared to the
solute.
● Fractional distillation is based on the significant difference in boiling points of miscible
liquids in a mixture.
Simple distillation Fractional distillation
Advantages ● simpler setup than
fractional
● faster distillation times
● consumes less energy
than fractional
distillation
● much better separation
between liquids than
simple distillation
● can more readily purify
complex mixtures than
simple distillation
Disadvantages ● requires the liquids to
have large boiling point
differences (>70​o​
C)
● more complicated setup
than simple distillation
● takes longer for liquids

3. ● gives poorer
separation than
fractional distillation
● only works well with
relatively pure liquids
to distill
● consumes more energy
than simple distillation
Best used for: separating relatively pure
liquids with large boiling
differences or liquids with solid
impurities
separating complex mixtures of
liquids with smaller boiling point
separations.
→ Sublimation
● Sublimation separates ​a mixture of solids​, one of which sublimes.
● A few substances change directly, from a solid to vapour on heating without going
through the liquid state.
● This change is called sublimation. On cooling, water vapour changes back to solid
directly.
● An example of a substance that sublimes: Iodine
● Sublimation is based on the principle that one substance in a mixture is able to
sublime while the rest of the mixture is stable to heat.
→ Magnetic attraction
● Magnetic attraction is based on the principle that one substance is attracted to a
magnet while the rest of the mixture is not.
→ Use of the separating funnel
● Use of the separating funnel is based on the miscibility of two different liquids.
● The denser liquid would be at the bottom while the less dense liquid would be at the
top
● The use of the separating funnel implies that the two liquids are not miscible
→ Rf value

4. ● Rf = (height or length the component travelled or eluted from the starting point) divided
by the total length the mobile phase or solvent travelled
→ Need to use locating agents in the chromatography of colourless compounds.
● Locating agent merge with colourless compounds (e.g. fatty acids) and make it visible
by naked eye or in presence of U.V light.
Kinetic Particle Theory (KPT)
→ Brief introduction:
1. The kinetic particle theory is a model that represents matter as small discrete particles,
which are in constant and random motion.
2. The states of matter are classified into solids, liquids and gases in terms of the
arrangement and movement of the particles.
3. Energy changes bring about corresponding changes in movement and arrangement of
particles. As temperature increases, the kinetic energy of the particles increases, and
vice versa. As a result, particles will move faster.
4. Diffusion is a physical phenomenon that provides evidence for the movement of
particles in liquids and gases.
→ Kinetic Particle Theory
● all matter is made up of small particles that cannot be seen directly with the naked eye
● there are spaces between particles in all matter but the amount of space in each state
of matter is different
● particles are in constant random motion, but the speed of movement differs in each
state
● particles possess kinetic energy that varies with temperature
● the average kinetic energy of all particles is directly proportional to the absolute
temperature.
→ States of Matter Comparison
Properties Solid Liquid Gas
Arrangement of
particles
Closely packed
together in an
orderly manner
Close together in a
disorderly manner,
in clusters
Far apart in a
random manner
Forces between
particles
Very strong Strong Negligible
Movement Vibrations about
fixed positions
Vibrations and
movement
Vibrations and
movement

5. increase as
temperature
increase
throughout the
liquid
anywhere
Energy of particles Less energy More than in solid More than in liquid
Density High (particles
close together)
High (particles
close together)
Low (particles far
apart)
Compressible? No No Yes
→ Pressure (Not tested I think but just in case)
● Randomly moving gas molecules collide with one another and with the inner surface of
the container which the gas fills. The collisions produce forces.
● The force acting on each unit area of the inner surface of the container is the gas
pressure exerted on it
● When the volume of gas is halved by halving the volume of its container, the number
of molecules per unit volume in the container will be doubled.
● The number of collisions between the gas molecules and the inner surface of the
container will double the force produced.
● Hence, the force acting on each unit area of the inner surface of the container, that is
the gas pressure, will be doubled.
● The relationship between the pressure and volume of a gas at constant temperature
and fixed mass is stated in Boyle's Law as follows
● For a fixed mass of gas at constant temperature, the pressure is inversely proportional
to its volume.