If 20 grams of zinc reacts with hydrochloric acid, how much zinc chloride is produced?

Assuming there is excess acid, the equation for the reaction is Zn + 2HCl - > ZnCl2 + H2.

Mols of zinc = 20/65 (mass/relative atomic mass)

Ratio of Zn : ZnCl2 = 1 : 1

Hence mols of Zinc = mols of Zinc chloride

Mass of ZnCl2 = (20/65) (65+71)

= 41.8g