A student investigates the reaction between calcium carbonate and dilute hydrochloric acid to produce carbon dioxide gas, CO2\text{CO}_2CO2, and a salt solution.
In each of three experiments, X, Y, and Z, she uses the same mass and surface area of calcium carbonate but varies the temperature of the reaction mixture.
Look at the graph of her results.
a.[1]
Look at the line for experiment Y on the graph. When is the rate of reaction greatest? Choose your answer from the list:
- 0 – 30 seconds
- 30 – 60 seconds
- 60 – 90 seconds
- 90 – 120 seconds
b.[2]
Look at the line for experiment Z. Calculate the average rate of reaction during the first 90 seconds. Give your answer to 2 significant figures.