Mole to mole ratio stoichiometry

Question

How many grams of zinc are needed to produce 20.8 grams of zinc chloride?

Answer 1

I'll assume the Zn is reacting with HCl as follows:

Zn(s) + 2HCl(aq) ==> ZnCl₂(aq) + H2(g) ... balanced equation

20.8 g ZnCl₂ x 1 mol ZnCl2/136 g x1 mol Zn/mol ZnCl₂ x 65.4 g Zn/mol = 10.0 g Zn needed (3 sig. figs.)