0.25 g of an organic compound "A" containing carbon, hydrogen and oxygen was analysed using the combustion method. There was an increase in mass of CaCl2 tube and potash tube at the end of the experiment. The amount was found to be 0.15 g and 0.1837 g, respectively. The percentage of oxygen in compound A is %. (Nearest integer) (Given: molar mass in g mol-1 H : 1, C : 12, O : 16)
Answer
73
Solution
CaCl2 tube absorbs H2O (0.15 g); potash (KOH) tube absorbs CO2 (0.1837 g).
Mass of H = 218 0.15 = 0.01667 g
Mass of C = 1244 0.1837 = 0.05010 g
⇒ Mass of O = 0.25 - 0.01667 - 0.05010 = 0.18323 g
∴ % O = 0.183230.25 100 = 73.3\% 73\%
Answer: 73