Question

I need help balancing equations.
_C7H60+_02->_C02+_H20

I don't know how to balance it because when i do it just won't work out ill have too much on one side and it just wouldn't work. i know im missing a rule or something.

Answer 1

Most of these just take a little practice. The more you practice the better you get. Here is what I do. First, I make sure to balance O2 LAST because since it is by itself I can put any number there I need.

C7H60 + 02-> C02 + H20

Start with C. I see 7 on the left so I know I must have a 7 for CO2.
C7H6O + O2 ==> 7CO2 + H2O

Now the H. There are 6 on the left so that means I must have 3H2O on the right.
C7H6O + O2 ==> 7CO2 + 3H2O

That balances C and H. Usually I check at this point to make sure they are ok. 7 C and 6 H on both sides. OK. Now, I count on the right to see how many O atoms I MUST have on the left. I see 17 O atoms (7*2=14 from CO2 and 3 from 3H2O = 17 total) on the right so I MUST have 17 on the left. There is 1 O in C7H6O which leaves 16 more on the left I must add. So, I place an 8 for O2.
C7H6O + 8O2 ==> 7CO2 + 3H2O

Now I check it to make sure I didn't goof somewhere. 7 C on the left and 7 on right.
6H left and right.
17 O left and 14+3 = 17 on right.
Everything ship shape.