S-Cool Revision Summary

S-Cool Revision Summary

Rate is a measure of the speed that a reaction takes place at. In other
words it is a measure of the change that happens in a single unit of time.

When measuring rate of a reaction we usually measure the amount of reactant
used up per unit
of time or the amount of product produced per unit of
time
.

When measuring the amount of product produced, a syringe can be used if the
product is a gas. Alternatively, if the gas is allowed to escape during the
reaction a measure of mass lost could be used to measure the rate.

The rate changes throughout the reaction.

The rate is greatest at the start, but gets less as the reaction proceeds.

Rate of reaction can be changed by:

  1. Change in concentration of reactants

  2. Change in temperature

  3. Change in surface area of reactants

  4. Use of a catalyst.

A reaction goes faster when the concentration of a reaction is increased.

A reaction proceeds at a quicker rate when the temperature is raised. When
the temperature increases by 10oC, the rate approximately doubles.

Increasing surface area of solid reactants, increases the rate of a reaction.

Catalysts increase the rate of a reaction by lowering the activation
energy. This means more successful collisions will take place over a period
of time.

A catalyst is a substance that changes the rate of a chemical reaction
but remains chemically unchanged.