Changing the rate of a reaction II

In many reactions, one of the reactants is a solid. The reaction between hydrochloric acid and calcium carbonate (marble chips) is one example. Carbon dioxide gas is produced  

The method Marble chips and add are placed in the flask, which is then plugged with cotton wool. This prevents any liquid from splashing out during the reaction. Next the flask is weighed. Then it is tipped up, to let the reactants mix, and a clock is started at the same time. The mass is noted at regular intervals, until the reaction is complete. 

Since carbon dioxide can escape through the cotton wool, the flask gets lighter as the reaction proceeds. So by weighing the flask, you can foUow the rate of the reaction. 

The experiment is repeated twice. Everything is kept exactly the same each time, except the surface area of the marble chips  

For experiment 1, large chips of marble are used. The surface area is the total area of the surface of these chips. 

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