Chapter 18 - Rates Of Reaction

Front 1

What is the rate of a reaction?

Back 1

The reaction rate is the change in the amount of reactants or products per unit time.

Front 2

How do you follow the rate of a reaction?

Back 2

1. Measure the volume of gas evolved
   
2. Measure the loss in mass as a gas is evolved.
   
3. Use colorimetry to measure colour change of a reaction.
   
4. Measure pH change of the reaction.
   

Front 3

How do you work out reaction rate from a concentration-time graph?

Back 3

Calculating the gradient at a certain point on the graph will give you the rate of reaction at that point.

If the graph is a curve, you will have to draw a tangent.

Front 4

How do you calculate the initial rate of reaction?

Back 4

• The initial rate of reaction is the rate at the start of the reaction.
  
• You can find this from a concentration-time graph by calculating the gradient from a tangent at time = 0.
  

Front 5

What is a clock reaction?

Back 5

1. In a clock reaction you measure how the time taken for a set amount of product to form changes as you vary the concentration of one of the reactants.
   
2. Usually an easily observable endpoint.
   
3. The quicker the clock reaction finishes, the faster the initial rate of reaction.
   

Front 6

What are the assumptions needed to make for a clock reaction?

Back 6

1. The concentration of each reactant doesn't change significantly over the time of your clock reaction.
   
2. The temperature stays constant.
   
3. When the endpoint is seen, the reaction hasn't proceeded too far.