Question

Aqueous aluminum bromide and solid zinc are produced by the reaction of solid aluminum and aqueous zinc bromide . write a balanced chemical equation for this reaction.

Answer 1

3 ZnBr2 (aq) + 2 Al (s) ==> 2 AlBr3 (aq) + 3 Zn (s) The unbalanced equation is: ZnBr2 (aq) + Al (s) ==> AlBr3 (aq) +Zn (s) First, count the atoms of each element on each side of the equation: Zn 1,1 Br 2,3 Al 1,1 The zinc and aluminum, but the bromine doesn't match with 2 and 3. So look for the least common multiple of 2 and 3 which is 6 and adjust the quantities on both sides to have 6 bromine atoms on both sides. Do this by having 3 zinc bromide on the left and 2 aluminum bromide on the right, getting: 3 ZnBr2 (aq) + Al (s) ==> 2 AlBr3 (aq) +Zn (s) Now check the atom counts again for both sides: Zn 3,1 Br 6,6 Al 1,2 Now bromine matches, but zinc and aluminum doesn't. But it's easy enough to add an extra aluminum to the left and 2 more zinc to the right. Giving: 3 ZnBr2 (aq) + 2 Al (s) ==> 2 AlBr3 (aq) + 3 Zn (s) Now check the atom counts again: Zn 3,3 Br 6,6 Al 2,2 And they match. So the balanced equation is: 3 ZnBr2 (aq) + 2 Al (s) ==> 2 AlBr3 (aq) + 3 Zn (s)