Question

Choose the correct option:

How many grams of water will be produced by complete combustion of 12 g of methane gas?

Options

• 16

• 27

• 36

• 56

Answer 1

27

Explanation:

\[\ce{CH4 + 2O2 -> CO2 + 2H2O}\]

1 mol of CH₄ = 2 mol of H₂O

12 g of CH₄ = ? grams of H₂O

molar mass of CH₄ = 12 + (1) × 4

= 12 + 4

= 16

mol = `"mass"/"molar mass"`

1 mol of CH₄ = `12/16 = 3/4` = 0.75 mol of CH₄

mole of H₂O = 2 × 0.75 = 1.50 mole of H₂O

molar mass of H₂O = (1) × 2 + 16

= 2 + 16

= 18

mole of H₂O = `"mass"/"molar mass"`

mass = 1.5 × 18

= 27.0 gram