5 g of zinc pieces are added to 400 cm³ of 0.5 mol. dm-3 hydrochloric acid. To investigate the average rate of the reaction, the change in the mass of the flask containing the since and the acid is measured by placing the flask on a direct reading balance. The reading on the balance shows that there is a decrease in mass during the reaction. The reaction which takes place is given by the following equation: Zn(s)+2HCl(aq)→ZnCl2(aq)+H2(g)

Why is there a decrease in mass during the reaction?

The experiment is repeated, this time using 5 g of powdered zinc instead of pieces of zinc. How will this influence the average rate reaction?

The experiment bus repeated once more,this time using 5 g of the zinc pieces of 600 cm³ of 0.5 mol.dm-3 hydrochloric acid. How does the average rate of this reaction compare with the original reaction rate?

What effect would a catalyst have on the average rate of this reaction?