A hydrocarbon CxHy combusts in excess oxygen. Write the balanced chemical equation for the reaction and determine the volume of remaining gas.

The combustion of a hydrocarbon $\text{C}_x\text{H}_y$ in excess oxygen can be represented by the general equation:

$$\text{C}_x\text{H}_y(g) + \left(x + \frac{y}{4}\right)\text{O}_2(g) \rightarrow x\text{CO}_2(g) + \frac{y}{2}\text{H}_2\text{O}(l)$$

Since the gas is cooled, water produced will condense into a liquid and its volume is negligible. The remaining gaseous products are carbon dioxide and any unreacted (excess) oxygen.

Step 1: Determine the volume of $\