*Acids and Bases*

Bronsted-Lowry acid: a hydrogen ion (proton) donor

Bronsted-Lowry base: a hydrogen ion (proton) acceptor

Lewis acid: an electron pair accepter

Lewis base: an electron pair donor

	Properties	Example
Strong Acid	Completely dissociates in water to donate protons. pH (1 – 3) Good conductor of electricity as has many free moving ions.	Hydrochloric acid, HCl HCl(aq) + H2O(l)  H3O+(aq) + Cl-(aq)
Weak Acid	Partially dissociates in water. pH (4 – 6) Poor conductor of electricity	Ethanoic acid, CH3COOH CH3COOH(aq) + H2O(l) ⇄ CH3COO-(aq) + H3O+(aq)
Strong Base	Readily accepts protons. pH (11 – 14) Good conductor of electricity due to many free moving ions.	Sodium hydroxide, NaOH NaOH(aq)  Na+(aq) + OH-(aq)
Weak Base	Partially accepts protons. pH (8 – 10) Poor conductor of electricity	Ammonia, NH3 NH3(aq) + H2O(l) ⇄NH4+(aq) + OH-(aq)

*Energetics*

The energy change for a reaction is given the symbol ΔH (units: kJ mol^-1)

Exothermic reactions: energy is released to the surroundings, negative ΔH.

Endothermic reactions: energy is absorbed from the surroundings, positive ΔH.

Activation energy, E_a = the minimum energy a particle must have to react

Using average bond energies to calculate ΔH:

ΔH = [total bonds broken in reactants] – [total bonds made in products]

*Kinetics*

The rate of a reaction is a measure of how fast or slow a reaction occurs.

Collision Theory: for a successful reaction to occur, particles must:

• collide

• with energy equal to or greater than the activation energy, E_a

• in the correct orientation

Rate of Reaction Graph

1. At first the gradient is steepest, the reaction is quickest, there are most reacting particles.

2. The gradient becomes less steep, the reaction slows, there are less reacting particles.

3. The gradient is horizontal, the reaction is complete, there are no reacting particles remaining.

Factors that increase the rate of reaction

Increase in Temperature: particles gain heat energy, move more quickly, collide more often, so there is increased chance of a successful collision. Also, more particles will have energy greater than the activation energy.

Increase in Concentration/Pressure: particles are closer together, therefore collide more often, so there is increased chance of a successful collision.

Increase in Surface Area: more particles are available to collide, therefore there are more collisions and an increased chance of a successful collision.

Addition of a Catalyst: provides an alternative route of lower activation energy, so more particles have energy equal to or greater than the activation energy, so there is an increased chance of a successful collision.