[archijun3]

When we make hydrogen in the lab, we can react zinc with hydrochloric acid to produce a salt and hydrogen.
And copper(II) sulphate is added, which reacts with a small amount of the zinc to form copper, which acts as the catalyst in the reaction.
Why can't we just add copper straight-away??

[Borek]

You want copper to be deposited on the zinc surface, this way it is more effective.