In the reaction 2C2H6 + 7O2 → 4CO2 + 6H2O, what mass of C2H6 is required to produce 280.0 g of CO2?

• A. 70.0 g
• B. 140 g
• C. 105 g
• D. 56.0 g

Answer: (A)

Verified step by step guidance

1. Identify the given chemical reaction: \$2C_2H_6 + 7O_2 \rightarrow 4CO_2 + 6H_2O$.
2. Determine the molar mass of \(CO_2\) by adding the atomic masses: Carbon (12.01 g/mol) and Oxygen (16.00 g/mol). So, \(M_{CO_2} = 12.01 + 2 \times 16.00\) g/mol.
3. Calculate the number of moles of \(CO_2\) produced using the given mass: \(n_{CO_2} = \frac{\text{mass of } CO_2}{M_{CO_2}}\).
4. Use the stoichiometric ratio from the balanced equation to find moles of \(C_2H_6\) needed: \(n_{C_2H_6} = n_{CO_2} \times \frac{2}{4}\) (since 2 moles of \(C_2H_6\) produce 4 moles of \(CO_2\)).
5. Calculate the mass of \(C_2H_6\) required by multiplying its moles by its molar mass: \(\text{mass of } C_2H_6 = n_{C_2H_6} \times M_{C_2H_6}\), where \(M_{C_2H_6} = 2 \times 12.01 + 6 \times 1.008\) g/mol.