Question

Chlorine is prepared in the laboratory by treating manganese dioxide (MnO₂) with aqueous hydrochloric acid according to the reaction.

How many grams of HCl react with 5.0 g of manganese dioxide?

(Atomic mass of Mn = 55 g).

Answer 1

1 mole of MnO₂ = 55 + 32 = 87 g. 

87 g of MnO₂ reacts with 4 moles of HCl. i.e. = 4 x 36.5 = 146 g of HCl. 

∴ 5 g of MnO₂ will react with 146/87 x 5.0 = 8.40 g.