Consider the reaction between zinc granules (lumps) and hydrochloric acid:
Zn(s) + 2HCl(aq) -> ZnCl2(aq) + H2(g)
By altering the conditions under which the reaction is carried out, we can change the rate at which hydrogen has is produced. Which of the following changes will NOT increase the rate of the production of hydrogen gas?
A Increasing the concentration of the acid
B Increasing the mass of zinc
C Increasing the temperature
D Using powdered zinc instead of zinc granules
Now, the answers say that the answer is B because "changing the total amount of either reactant will not change the rate of the reaction, although it will of course affect the amount of products produced. However, as zinc is a solid reactant, increasing its total surface area will increase its rate of reaction, since the reaction can only occur at its surface."
But, if there is more mass (ie. more reactant), doesn't that mean that there are more particles present per amount of HCl, thus more collisions between particles, hence more successful collisions and a faster rate of reaction?
I'm confused! I got the answer B only because of process of elimination (the others are clearly wrong), but after looking over it again, it doesn't seem to make sense!