Pradyun Singh (Period 3, Semester 2)
Gases
IMF
Solutions
Kinetic Molecular Theory
Average kinetic energy is same at certain temperature
Gas particles are always in motion
No attraction between the gas molecules
The gas particles don't have volume
Collisions are elastic so no energy is lost
Ideal Gases
Seen at high temperature and low pressure
Imaginary Gases
Boyle's Law
Pressure is inversely related to volume
p1v1 = p2v2
Charles' Law
Volume is directly proportional to temperature
Gay Lussac's Law
Pressure directly proportional to temperatuer
Avogadro' Law
volume and moles are directly proprtional
Diffusion
Gases mixing
Heavier gases diffuse slower
Effusion
Gases escaping through a pinhole
Heavier gases effuse slower
Forces between two molecules
4 main types of IMF
London Dispersion Forces
Hydrogen Bonding
Dipole-Dipole
Ion-Dipole
Increase with increased molar mass as greater polarizabilty
Bond between hydrogen and F,O,N
Between 2 polar substances
Stronger than dipole-diple and London forces
All molecules have london forces
momentary induced dipoles
Determines state of molecules
Stronger IMF has increased boiling and melting point
Larger charge is a stronger attraction
Permanent
Phase Diagram
Triple point is where all 3 states are possible
temp constant during phase change
Boiling occurs when vapor pressure = atmospheric pressure
Homogeneous mixture
Solute dissolves in solvent
Solvent is medium which solute dissolved in
Numerous ways of expressing solutions
Molarity is moles of solute/ liter of solution
Molality is moles of solute / kg of solvent
Mole fraction is mol of solute/ mol of solute + solvent
mass solute/ mass solution * 100%
Energetics of Solutions
delta H of solutions = delta H of solute + delta H of solvent + delta H of mix
deltaH solute and delta H solvent are both endothermic as overcoming attractions
delta H mix is exothermic as new attractions
Like dissolves like
Factors favoring solutions forming
Exothermic, increase entropy
Vapor Pressure at surface of liquid
At equilibirum rate of condensation = rate of vaporization
Raoult's Law
A nonvolatile solute lowers vapor pressure of solvent
Psolution = Xsolvent * Psolvent
Both volatile
Ptotal = XaPa + XbPb
Ideal solution is when delta H = 0
Negative deviation is when lower than predicted
Solute, solvent is similar so strong attraction. Delta H solution is large and negative
Positive deviation is when higher than predicted. Solute and solvent are dissimilar
Solubility of solids increase with temperatuer
Solubility of gases decrease with increased temperature
Solubility of gases increase with increased pressure