What is the mass of zinc chloride obtained if 20 grams of 70% hydrochloric acid reacted with zinc?

1. We compose the reaction equation:
Zn + 2HCl = ZnCl2 + H2 ↑;
2. Let’s calculate the mass of hydrogen chloride:
m (HCl) = w (HCl) * m (hydrochloric acid) = 0.7 * 20 = 14 g;
3. Let’s find the chemical amounts of hydrogen chloride and zinc chloride:
n (HCl) = m (HCl): M (HCl) = 14: 36.5 = 0.3836 mol;
n (ZnCl2) = n (HCl) = 0.3836 mol;
4. Calculate the mass of the resulting salt:
m (ZnCl2) = n (ZnCl2) * M (ZnCl2);
M (ZnCl2) = 65 + 35.5 * 2 = 136 g / mol;
m (ZnCl2) = 0.3836 * 136 = 52.17 g.
Answer: 52.17 g.