Answer
$C_6H_5OH(s) + 7O_2(g) --> 6CO_2(g) + 3H_2O(l)$
Work Step by Step
1. Write the unbalanced equation:
* Since it is a combustion, the phenol will react with oxygen, and produce CO2 and water.
$C_6H_5OH (s) + O_2 (g) --> CO_2(g) + H_2O(l)$
2. In a combustion, you start balancing the number o Carbon atoms:
$C_6H_5OH + O_2 --> 6CO_2 + H_2O$
3. Now, fix the number of Hydrogen atoms:
$C_6H_5OH + O_2 --> 6CO_2 + 3H_2O$
4. Finally, balance the number of oxygen atoms:
$C_6H_5OH + 7O_2 --> 6CO_2 + 3H_2O$
