This is a single displacement reaction
aluminum + hydrochloric acid -->
The Attempt at a Solution
Since I know its single displacement, and I know that aluminum can't trade places with chlorine because one is a metal and one is a non-metal, aluminum must trade places with hydrogen, which I know can trade places with a metal.
Al + HCl --> H + AlCl
Since I know that hydrogen is a diatomic element, I must change it to H2
Al + HCl --> H2 + AlCl
Now it's out of balance because there are 2 hydrogens on the right. So I balance it by multiplying the left HCl by 2.
Al + 2HCl --> H2 + AlCl
This leaves Cl out of balance, so I multiply the right one by 2.
Al + 2HCl --> H2 + 2AlCl
This leaves Al out of balance, so I multiply the left one by 2.
2Al + 2HCl --> H2 + 2AlCl
Seems to be balanced now. But when I look up the answer by Googling, I find that I should have ended up with
2Al + 6HCl --> 2AlCl3 + 3H2
Where did I go wrong? Thanks!