Question

Mass of methane required to produce 22 g of CO₂​ after complete combustion is ______ g.
(Given Molar mass in g mol⁻¹: C=12.0, H=1.0, O=16.0).

Answer 1

Correct Answer: 8

The balanced chemical equation for the combustion of methane (CH₄) is: CH₄ + 2O₂ → CO₂ + 2H₂O. To determine the mass of methane needed to yield 22 g of CO₂, follow these steps:

Step 1: Calculate the molar mass of CO₂

Molar mass of CO₂ = Molar mass of C + 2 × Molar mass of O = 12.0 g/mol + 2 × 16.0 g/mol = 44.0 g/mol.

Step 2: Compute the moles of CO₂ produced

Moles of CO₂ = Mass of CO₂ / Molar mass of CO₂ = 22 g / 44.0 g/mol = 0.5 mol.

Step 3: Apply reaction stoichiometry to find moles of CH₄

From the balanced equation, 1 mole of CH₄ produces 1 mole of CO₂. Thus, 0.5 mol of CO₂ requires 0.5 mol of CH₄.

Step 4: Determine the mass of CH₄

Molar mass of CH₄ = Molar mass of C + 4 × Molar mass of H = 12.0 g/mol + 4 × 1.0 g/mol = 16.0 g/mol.

Mass of CH₄ = Moles of CH₄ × Molar mass of CH₄ = 0.5 mol × 16.0 g/mol = 8 g.

The required mass of methane is 8 g.