The rate of a chemical reaction can be raised by increasing the surface area of a solid reactant. This is done by cutting the substance into small pieces, or by grinding it into a powder.
If the surface area of a reactant is increased:
Compared to a reaction with lumps of reactant, the graph line for the same reaction but with powdered reactant:
This shows that the rate of reaction is greater when the surface area is increased.
The reactions will produce the same volume if all of the reactant factors are the same, ie mass of solid, volume of acid. If one of the factors is halved, the volume produced will be half as much. If the factor is doubled, the reaction will produce double the volume.
This applies to all factors that can alter the rate.