If 5.0 moles of C_3H_8 react completely with oxygen, how many molecules of H_2O are formed?

• A. 9.0 × 10^{24} molecules
• B. 6.0 × 10^{24} molecules
• C. 1.5 × 10^{25} molecules
• D. 3.0 × 10^{24} molecules

Answer: (A)

Verified step by step guidance

1. Write the balanced chemical equation for the combustion of propane (C_3H_8) with oxygen (O_2). The general form is: \(\mathrm{C_3H_8} + \mathrm{O_2} \rightarrow \mathrm{CO_2} + \mathrm{H_2O}\).
2. Balance the equation by ensuring the number of atoms of each element is the same on both sides. For propane combustion, the balanced equation is: \(\mathrm{C_3H_8} + 5\mathrm{O_2} \rightarrow 3\mathrm{CO_2} + 4\mathrm{H_2O}\).
3. Identify the mole ratio between propane and water from the balanced equation. For every 1 mole of C_3H_8, 4 moles of H_2O are produced.
4. Calculate the moles of water produced from 5.0 moles of propane using the mole ratio: \$5.0 \text{ moles C}_3\text{H}_8 \times \frac{4 \text{ moles H}_2\text{O}}{1 \text{ mole C}_3\text{H}_8}$.
5. Convert the moles of water to molecules using Avogadro's number: \(\text{molecules of H}_2\text{O} = \text{moles of H}_2\text{O} \times 6.022 \times 10^{23} \text{ molecules/mole}\).