Given the reaction: CaC2 + 2 H2O → C2H2 + Ca(OH)2, how many grams of H2O are required to produce 13.0 g of C2H2?

• A. 13.5 g
• B. 10.8 g
• C. 12.0 g
• D. 8.0 g

Answer: (B)

Verified step by step guidance

1. Identify the given chemical reaction: \(\text{CaC}_2 + 2 \text{H}_2\text{O} \rightarrow \text{C}_2\text{H}_2 + \text{Ca(OH)}_2\).
2. Determine the molar mass of acetylene (\(\text{C}_2\text{H}_2\)) by adding the atomic masses of 2 carbons and 2 hydrogens.
3. Calculate the number of moles of \(\text{C}_2\text{H}_2\) produced using the formula: \(\text{moles} = \frac{\text{mass}}{\text{molar mass}}\), where the mass is 13.0 g.
4. Use the stoichiometric coefficients from the balanced equation to find the moles of \(\text{H}_2\text{O}\) required. Since 2 moles of \(\text{H}_2\text{O}\) produce 1 mole of \(\text{C}_2\text{H}_2\), multiply the moles of \(\text{C}_2\text{H}_2\) by 2.
5. Calculate the mass of \(\text{H}_2\text{O}\) needed by multiplying the moles of \(\text{H}_2\text{O}\) by its molar mass (approximately 18.0 g/mol).