Asked by Angeline
                My teacher says the correct way to predict/balance the equation AL+HCL yields H+AlCl3 is to balance it like this: 2Al+6HCl yields 3H2+2AlCl3.  I don't get why there is a two in front of the AlCl3.  Could you guide me through the logic of this please? 
            
            
        Answers
                    Answered by
            DrBob222
            
    Surely.
You have 2 Al on the left; therefore, there must be a 2 for 2AlCl3 to keep the Al atoms the same on both sides.
Second reason:
There are 6 Cl atoms on the left (from 6HCl) and there must be 6 Cl atoms on the right. A 2 coefficient for 2AlCl3 gives 2 Al and 6 Cl in one swell foop.
    
You have 2 Al on the left; therefore, there must be a 2 for 2AlCl3 to keep the Al atoms the same on both sides.
Second reason:
There are 6 Cl atoms on the left (from 6HCl) and there must be 6 Cl atoms on the right. A 2 coefficient for 2AlCl3 gives 2 Al and 6 Cl in one swell foop.
                    Answered by
            Angeline
            
    I'm still a little unsure in front of the first Al why there's a two.  Could you explain?
    
                    Answered by
            lyne
            
    Since you have the cooefficient of 6 before HCl, you must have 6 Cl atoms on the other side as well.  
AlCl3 already has 3 Cl atoms so if you put a 2 as the coefficient that gives you 6 (2 x 3 =6).
You have balanced the Cl atoms but now you have unbalanced Al atoms. If you put a 2 in front of the first Al then it balances.
post if you still don't understand
    
AlCl3 already has 3 Cl atoms so if you put a 2 as the coefficient that gives you 6 (2 x 3 =6).
You have balanced the Cl atoms but now you have unbalanced Al atoms. If you put a 2 in front of the first Al then it balances.
post if you still don't understand
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