3.77 When benzene, C6H6, with bromine, Br2, bromobenzene, C6H5Br, is obtained:
C6H6 + Br2 ----> C6H5Br + HBr
(a) What is the theoretical yield of bromobenzene in this reaction when 30.0 g benzene reacts with 65.0 g bromine?
to find the theoretical yield, we find the limiting reactant: here we convert the given amount of benzene to bromine and vice vera to find out which we'll run out of first:
convert 30.0 g benzene to bromine:
need 61.4 g bromine - we have 65 g
convert 65.0 g bromine to benzene:
need 31.8 g benzene - we only have 30.0 g!
benzene is the limiting reactant! Now, convert g benzene to g bromobenzene:
the theoretical yield of bromobenzene is 60.3 g.
(b) if the actual yield of bromobenzene was 42.3 g, what was the percentage yield?
percent yield is given as (actual yield/theoretical yield) * 100, so
the per cent yield is 70.1%