Question

3. In a chalk piece, the amount of Calcium=10 g, the amount of Carbon = 3 g, the amount of Oxygen = 12 g ……..Find the percentage of carbon in the chalk.

Answer 1

chemical formula of chalk pieces = CaCO3

so, molecular mass of CaCO3 ( chalk ) = (40 + 12 + 48 )g/mol = 100g /mol

total mass of chalk given = 10g + 3g +12g
= 25 g

% of carbon = mass of C /total mass × 100 = 3/25 × 100 = 12 ℅

Answer 2

Molecular formula of chalk pieces = CaCO₃

Total mass of chalk given = 10g + 3g +12g = 25 g


% of carbon = mass of C /total mass × 100% = 3/25 × 100% = 12 %