Questions: Let's start by balancing the following chemical reaction fill in blank C2H5OH(l)+ fill in blank O2(g) → fill in blank. CO2(g)+ fill in blank H2O(g)

Solution Steps

The unbalanced chemical equation for the combustion of ethanol ($\mathrm{C}_2\mathrm{H}_5\mathrm{OH}$) is: $$\mathrm{C}_2\mathrm{H}_5\mathrm{OH}(l) + \mathrm{O}_2(g) \rightarrow \mathrm{CO}_2(g) + \mathrm{H}_2\mathrm{O}(g)$$

Ethanol contains 2 carbon atoms, so we need 2 $\mathrm{CO}_2$ molecules on the product side: $$\mathrm{C}_2\mathrm{H}_5\mathrm{OH}(l) + \mathrm{O}_2(g) \rightarrow 2\mathrm{CO}_2(g) + \mathrm{H}_2\mathrm{O}(g)$$

Ethanol contains 6 hydrogen atoms, so we need 3 $\mathrm{H}_2\mathrm{O}$ molecules on the product side: $$\mathrm{C}_2\mathrm{H}_5\mathrm{OH}(l) + \mathrm{O}_2(g) \rightarrow 2\mathrm{CO}_2(g) + 3\mathrm{H}_2\mathrm{O}(g)$$

Now, count the oxygen atoms on the product side: $2 \times 2$ from $\mathrm{CO}_2$ and $3 \times 1$ from $\mathrm{H}_2\mathrm{O}$, totaling 7 oxygen atoms. Ethanol provides 1 oxygen atom, so we need 6 more from $\mathrm{O}_2$, which means 3 $\mathrm{O}_2$ molecules: $$\mathrm{C}_2\mathrm{H}_5\mathrm{OH}(l) + 3\mathrm{O}_2(g) \rightarrow 2\mathrm{CO}_2(g) + 3\mathrm{H}_2\mathrm{O}(g)$$

Final Answer