Question

In laboratory preparation of chlorine, manganese dioxide (MnO₂) reacts with aqueous hydrochloric acid according to the reaction:
4HCl (aq) + MnO₂ (s) → 2H₂O(l) + MnCl₂ (aq) + Cl₂ (g)
How many grams of HCl react with 5.0 g of manganese dioxide?

Answer 1

1 mol of MnO₂ = (Atomic mass of Mn + 2 x atomic mass of oxygen)
= 55 + 32 g = 87 g
87g of MnO₂ react with 4 moles of HCl i.e. 4 x 36.5 g
= 146 g of HCl.
(Molar mass of HCl is 36.5)
5.0 g of MnO₂ will react with HCl = 146/87 x 5.0 g
=8.40 g.