1. Monitoring the Rate of a Reaction
S2/3 Chemistry
Monitoring the Rate of a Reaction

2. Progress of a Reaction
The reaction to be studied is between pieces of marble and hydrochloric acid.
Calcium carbonate + hydrochloric acid calcium chloride +
water +
carbon dioxide
CaCO3 + HCl CaCl2 + H2O + CO2

3. Progress of a reaction
The reaction is followed by measuring the total volume of gas every 2 minutes.

5. Progress of a Reaction
The steeper the graph, the faster the reaction rate.

6. Calculating the Rate
Rate of Reaction is the change in quantity of a reactant or product per unit of time

7. Calculating the Rate
Since the rate of reaction is changing all the time you can only calculate the average rate during any time interval.
average rate = change in quantity
change in time

8. Calculating the Rate
The units used for rate depends upon which type of quantity is involved (mass, volume or concentration)

9. Calculating the Rate
Calculate the rate of reaction for the first two minutes

10. Calculating the Rate
Calculate the rate of reaction for the first two minutes
40 cm3 = 20cm3/min
2 min

11. Calculating the Rate
Calculate the rate of reaction for the second two minutes

12. Calculating the Rate
Calculate the rate of reaction for the second two minutes
20cm3 = 10cm3/min
2 min

13. Calculating the Rate
The reaction rate is highest at the start of the reaction
The rate of reaction is never constant
The rate of reaction decreases quickly at the start
The rate of the reaction is 0 when the reaction has stopped.