Most collisions do not lead to a reaction. - Reaction won't take place unless 1) They collide in the right direction. 2) They collide with at least a certain amount of energy. Increase Temperature Small increase in temperature can lead to a big change in rate of reaction. - More kinetic energy - Particles move faster - MANY MORE particles have energy greater than the activation energy and are able to react. Increase Concentration or Pressure - Particles closer together - More chance of a collision. - More chance of effective reaction. Increase Surface Area If in big lump, most particles won't collide with other reactants. Crush lumps; more particles in contact with other reactants. - Smaller particle size. - Larger surface area. - More particles likely to collide - More chance of effective reaction. - Faster rate of reaction. Catalysts - Activation energy lower. - Particles need lower energy to react - More particles have energy greater than the activation energy. - More particels likely to collide - More chance of effective reaction. Investigating Reaction Rates ~Measure... Volume of gas or decrease in mass. ~Time... How long it takes for precipitate to form.
# As reactants get used up, forward reaction slows down.
# As more product formed, reverse reaction speeds up.
DYNAMIC EQUILIBRIUM: Forward and backward reactions happen at the same rate.
Catalysts don't affect the position of equilibrium. Can't increase the yield - means equilibrium is reached faster.
Concentration - Increase concentration of a reactant, equilibrium tries to get rid of extra reactant. It makes more product. Equilibrium's shifted to the right.
- Increase concentratation of a product, equilibrium tries to remove extra product. Reverse reaction faster. Equilibrium shifts left.
- Decreasing concentration has opposite effect.