Question

When an aqueous solution of KBr is electrolyzed,

Answer 1

KBr + H2O = KOH + Br2 + H2

So we know that we need a 2 on the left of kbr so it would equal the right Br.

=2KBr
 now put a 2 in front of KOH since we need a 2k on right side

Now we put a 2 infront of H2O which wil make 4 h's and 2 o's

2h2o 

now it is balanced

2KBr + 2H2O = 2KOH + Br2 + H2