If 60 grams of ethane (C_2H_6, molar mass 30 grams/mol) react completely with excess oxygen according to the equation 2 C_2H_6 + 7 O_2 → 4 CO_2 + 6 H_2O, how many moles of CO_2 are produced?

• A. 7 moles
• B. 2 moles
• C. 4 moles
• D. 6 moles

Answer: (C)

Verified step by step guidance

1. Identify the given information: mass of ethane (C\_2H\_6) is 60 grams, and the molar mass of ethane is 30 grams/mol.
2. Calculate the number of moles of ethane by using the formula: \(\text{moles of ethane} = \frac{\text{mass of ethane}}{\text{molar mass of ethane}} = \frac{60}{30}\).
3. Write down the balanced chemical equation: \$2\ \mathrm{C_2H_6} + 7\ \mathrm{O_2} \rightarrow 4\ \mathrm{CO_2} + 6\ \mathrm{H_2O}$.
4. Use the mole ratio from the balanced equation to relate moles of ethane to moles of carbon dioxide: from the equation, 2 moles of ethane produce 4 moles of CO\_2, so 1 mole of ethane produces 2 moles of CO\_2.
5. Multiply the moles of ethane calculated in step 2 by the mole ratio (2 moles CO\_2 per mole ethane) to find the moles of CO\_2 produced.