What is the percent yield of iron chloride if we start with 34 g iron bromide and produce 4 g iron chloride? A reaction is shown. F e B r subscript 2 plus 2 K C l forms F e C l subscript 2 plus 2 K B r. A reaction is shown. F e B r subscript 2 plus 2 K C l forms F e C l subscript 2 plus 2 K B r.