Complete combustion of X g of an organic compound gave 0.25 g of CO2 and 0.12 g of H2O. If the % of carbon is 25% and of hydrogen is 4.89%, then X = 10-3 g. (Nearest integer) (Molar mass of C, H and O are 12, 1 and 16 g mol-1 respectively.)
- 273
- 27
- 2730
- 227
Answer
(1) 273
Solution
Mass of C in 0.25 g CO2 = 1244 0.25 = 0.06818 g
% C = 0.06818X 100 = 25
⇒ X = 0.06818 10025 = 0.2727 g ≈ 273 10-3 g
Check with H: mass of H = 218 0.12 = 0.01333 g ⇒ % H = 0.013330.2727 100 = 4.89% ✓
Answer: (1)