How do I balance the equation: C6H5COOH + O2 = CO2 + H2O? Also, are there a general set of rules that I can adopt.

The equation that needs to be balanced is: C6H5COOH + O2
--> CO2 + H2O

To balance these kind of equations
follow these steps:

• First balance the carbon
  atoms on both the sides. So the number of CO2 molecules on the right hand side would be
  equal to the number of C atoms on the left hand
  side.

• Next balance the number of
  hydrogen atoms on both the sides. The number of H2O molecules on the right hand side
  would be half the number of H atoms on the left hand
  side.

• Now add the number of O atoms
  on the right hand side, and subtract the O atoms not present as O2 molecules on the left
  hand side. Half of the number you get by doing this is the number of O2 molecules on the
  left hand side.

• In case it is not
  possible to balance the equation as you get fractions for any of the molecules you may
  have to use multiples of the numbers.

Using the
steps listed above, the balanced form of the given equation
is:

2C6H5COOH + 15O2 --> 14CO2 +
6H2O