Module 6 Flashcards
Kinetic Molecular Theory
1) The molecules in a gas are small and very far apart.
2) The molecules are in constant random motion.
3) Molecules collide with each other and with the walls of the container.
4) When collisions occur, kinetic energy is conserved (the collisions are perfectly elastic).
5) The molecules exert no attractive or repulsive forces on one another except during the process of collision. Between collisions, the molecules move in straight lines.
6) The average translational kinetic energy of the molecules is proportional to the Kelvin temperature. Avg Ek = (3/2)RT
The Ideal Gas Law
PV=nRT
Pressure (P)
Force per unit area.
Volume (V)
Provides a measure of the space occupied. In litres.
Kelvin Temperature (T)
Provides a measure of the average translational kinetic energy of the molecules in a sample. Avg Ek = (3/2)RT
Intermolecular Forces
Attractions between molecules that hold them together.
R
Universal gas constant.
All Gas Systems at Constant T and P
The volume ratio is equal to the mole ratio.
P Total
Ptot = PA + PB + PC
Ratio for Partial Pressures
PA = (na/ntot) x Ptot
The Ideal Gas Model Neglects
1) The size of the molecules.
2) Intermolecular forces.
Real Gas Equation (Van der Waals)
(P + an^2/V^2) x (V - nb) = nRT
a
Provides a measure of the strength of the intermolecular forces.
b
Provides a measure of the sizes of the molecules.
Compressibility Factor (Z)
Tells us how gas samples deviate from ideal behaviour. PV/nRT. Is 1 for an ideal gas.
Condensation
Gas to liquid.
Vaporization
Liquid to gas. Requires an input of energy.
Deposition
Gas to solid.
Sublimation
Solid to gas. Requires an input of energy.
Fusion
Solid to liquid. Requires an input of energy.
Freezing
Liquid to solid.
STP
Standard temperature and pressure (0 °C and 100 kPa).
SATP
Standard ambient temperature and pressure (25 °C and 100 kPa).
Vapour Pressure
Pressure of vapour that forms above a liquid in a closed container.
Normal Boiling Point (Tvap)
Temperature at which the vapour pressure of the liquid equals 1 atm (the boiling point at 1 atm).
Surface Tension (γ)
Energy required to increase the surface area of a liquid.
Viscosity (η)
Provides a measure of a fluid’s resistance to flow.
Polarizability (α)
A measure of the extent to which its charge cloud can be distorted (polarized) by another molecule. How squishy is the electron cloud.
Intermolecular Forces
Attractive forces between molecules.
Dipole Moment (µ)
The permanent uneven distribution of electron density.
Dipole-Dipole Forces
When molecules possess a permanent dipole moment.
London Dispersion Forces (LDFs)
Present in every molecule. The electron density shifts and changes creating non-permanent dipole moments.
Hydrogen Bond
When H is bonded to N, O, or F.
