Chemistry Hobbs
Lecture 1
Phases and Phase Equilibria
3 Phases
Gas
Liquid
Solid
Under given conditions of pressure and temperature a material will be found in one of these states depending on...
Intermolecular forces
Kinetic Energy
A phase is a form of matter that is uniform throughout in chemical composition and physical state
Kinetic energy is directly proportional to temperature
These are attractive forces within the molecules which fight agents kinetic energy
A phase transition is the spontaneous conversion of one phase to another phase. Occurs at a characteristic temperature for a given pressure
Heating Curves
X-axis
Y-axis
Energy
Temperature
The slope of the line = The inverse specific heat capacity for that phase
Vapour Pressure
the pressure exerted by the vapour at equilibrium with its condensed phase at a given temperature
Intermolecular Forces rise
Temperature rise
Lowers
Rises
Solid - Gas Equilibria
When kinetic energy and the pressure is high enough sublimation occurs
This converts the solid straight to a gas
Phase Diagrams
Critical Point
This is where the gaseous and liquid phase merge together under a great deal of temperature and pressure
Clausius-Clapeyron Equation
R=Gas Constant
H=Enthalpy of Vaporisation
T=Temperature (Kelvin)
p=Pressure
Lecture 2
Solution
A homogenous mixture, with no boundaries separating it's components
Heterogeneous Mixture
A mixture in which there are boundaries separating its components
Solute
Solvent
minority component
majority component
Concentrations
amount of solute dissolved in a solvent
Molarity (M)
Molality (m)
Molar Fraction
No. of Moles of Solute
L of Solution
No. of Moles of Solute
Mass (Kg) of Solvent
No. of moles of solute
No. of moles of solvent and solute
Solubility
The maximum amount of solute that can dissolve in a solvent at a given temperature
Why do solutions form
a solute will spontaneously dissolve if the formation of a solution leads to the lowering of the total Gibbs Energy
Entropy
Is the number of ways in which a system can distribute it's energy
A solvent normally has higher entropy than the pure solute and solvent
Solvents are usually entropically favoured
Dissolving Salts
The salt needs to be split into positive and negative ions to calculate enthalpy
Ideal and Ideal Dilute Solutions
Rate of Vaporisation = kx
Rate of Condensation = kp
@ equilibrium they equal each other
Raoult's Law
Pa=Vapor Pressure of Solvent
Xa=Mole Fraction of A
P*a=Vapour Pressure of Pure Solvent A
Ideal Solution is a solution that obey Rault's law throughout the composition range from pure A to pure B
Ideal Dilute Solutions
Henry's Law
Solutions which obeys Raoult's Law and the solute obeys Henry's Law
Pressure increases the solubility of gasses
Lecture 4
Colligative Properties
A collative property of a solution depends not on the nature of the chemical species dissolved in the solution but only the amount of solute dissolved in the solute
E.g.
Vapaur Pressure Lowering
Boiling Point Elevation
Freezing Point Elevation
Osmosis
Change in Bp/Fp = (Kb/Kf)(mb)
Osmatic Pressure is the hydrostatic pressure due to h
Lecture 4
Liquid Vapour Phase Diagrams
click to edit
Lecture 6
Chemical Equilibria
The System must be closed
It's reached spontaneously
It shows no visual change
Found at a certain temperature
Reaction shifting
Towards Products
Towards Reactants
Q increases
Q Decreases
Q<K
Q>K
Q=K
@ Equilibrium
increase product formation until eq. is increased
Increase reactant to reach eq.
Gibbs Free Energy
G<0
G=0
G>0
Spontanious
Equilibrium
Not Sponatnious