What is the mass percentage of carbon (C) in methane (CH4)? (The molar mass of carbon is

JAMB Chemistry 2023 55 views

What is the mass percentage of carbon (C) in methane (CH4)? (The molar mass of carbon is approximately 12 g/mol.)

  1. 12%
  2. 25%
  3. 50%
  4. 75% ✓

Explanation

Step 1: Calculate molar mass of methane (CH₄)
Carbon (C): 1 × 12 = 12 g/mol
Hydrogen (H): 4 × 1 = 4 g/mol
Total molar mass = 12 + 4 = 16 g/mol

Step 2: Find mass of carbon in the compound
Mass of carbon = 12 g/mol (only one carbon atom)

Step 3: Calculate percentage by mass
Mass percentage = (mass of carbon / total mass) × 100
= (12 / 16) × 100
= 0.75 × 100 = 75%

Conclusion: Carbon makes up three-quarters of methane’s mass. The four hydrogen atoms together contribute only 25% of the total mass.

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