Question

Chlorine gas can be prepared in the laboratory by the reaction of hydrochloric acid with manganese(IV) oxide. 4HCl(aq)+MnO2(s)⟶MnCl2(aq)+2H2O(l)+Cl2(g) A sample of 33.9 g MnO2 is added to a solution containing 45.5 g HCl. What is the limiting reactant? MnO2 HCl What is the theoretical yield of Cl2? theoretical yield: g Cl2 If the yield of the reaction is 86.9%, what is the actual yield of chlorine? actual yield

Answer 1

4 HCl (aq)   +   MnO2(s) --------------> MnCl2(aq)+2H2O(l)+Cl2(g)

145.84 g          86.9368 g                                                      70.906 g

45.5 g               33.9 g

145.84 g HCl   -----------> 86.9368 g MnO2

45.5 g HCl     --------------> ??

mass of MnO2 needed = 45.5 x 86.9368 / 145.84

                         = 27.1 g

but here we have 33.9 g . so this is excess .

limiting reagent is HCl

What is the theoretical yield of Cl2? theoretical yield:

145.84 g HCl   -----------> 70.906 g Cl2

45.5 g HCl     --------------> ??

theoretical yield of Cl2 = 45.5 x 70.906 / 145.84

theoretical yield of Cl2 = 22.1 g

% yield = (actual / theoretical) x 100

86.9 = (actual / 22.1) x 100

Actual yield = 19.2 g