Chemistry: moles and mass.

Question

If three (3) grams of solid Zinc (Zn) is mixed with fifty (50) milliliters of Hydrochloric acid (HCl), how much Zinc Chloride (ZnCl2) will be produced in grams?

Answer 1

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

3 grams of Zn x 1 mol Zn/65 g = 0.0462 moles Zn

moles HCl needed = 0.0462 mol Zn x 2 mol HCl/mol Zn = 0.0924 mols HCl needed

Volume HCl: (x L)(3 mol/L) = 0.0924 moles

x = 0.0308 L = 30.8 mls of HCl needed