Finding Reaction Rates from Graphs

Representing Rates of Reaction

• Graphs can represent rates of reaction.

• We can draw a graph of product (or reactant) against time in order to represent the rate of reaction.

• The gradient of the graph will be the rate of reaction.

  • The steeper the gradient, the faster the rate of reaction.

• Mean rate of reaction can be calculated.

• If we work out the overall change in y value (i.e. product formed or reactants used up) then divide by the total time taken for the reaction, we can calculate the mean rate of reaction.

Using Graph to make calculation

1.Identify the values on the graph.

• Identify the final volume of gas made from the graph, and the final time taken to make this volume.

• This is shown by the lines in red. The final volume = 70 cm3 and the time taken to make this volume is 80 seconds.

2. Write out the equation. Now, we can write out the equation to calculate a value for the rate of reaction.

• Mean rate of reaction = overall change in volume/change in time

3. Substitute in the numbers.

• Now that we have identified the correct equation, we can substitute in our numbers.

Mean rate of reaction = (70)/(80)