WAEC - Chemistry (1989 - No. 18)
The rate of the hydrogen in the reaction Zn(s) + 2HCI (aq) → ZnCI 2(g) + H 2(aq) + H 2(g) can be increased by
using Zinc powder instead of Zinc granules
using dilute instead of concentrated hydrochloric acid
cooling the container in which the mixture is placed
using an alloy of zinc instead of pure zinc
using hydrogen chloride gas instead of hydrochloric acid solution