Estimation of Carbon, Hydrogen, Nitrogen, Sulphur, Phosphorus — Prelims Questions

In Liebig's method for the estimation of carbon and hydrogen, 0.246 g of an organic compound gave 0.198 g of water and 0.440 g of carbon dioxide. Calculate the percentage of carbon and hydrogen in the compound.

In the Dumas method, 0.30 g of an organic compound gave 50 mL of nitrogen collected at 27°C and 750 mmHg pressure. If the aqueous tension at 27°C is 10 mmHg, calculate the percentage of nitrogen in the compound. (Atomic mass of N = 14)

0.32 g of an organic compound containing sulphur yielded 0.466 g of BaSO$_4$ in Carius method. Calculate the percentage of sulphur in the compound. (Atomic mass of S = 32, Ba = 137, O = 16)

Which of the following compounds CANNOT be estimated for nitrogen using Kjeldahl's method?

In the Carius method for phosphorus estimation, 0.45 g of an organic compound gave 0.666 g of magnesium pyrophosphate (Mg$_2$P$_2$O$_7$). Calculate the percentage of phosphorus in the compound. (Atomic mass of P = 31, Mg = 24, O = 16)

In the Kjeldahl's method, 0.4 g of an organic compound was digested. The ammonia evolved was absorbed in 60 mL of 0.1 N H$_2$SO$_4$. The excess acid required 25 mL of 0.1 N NaOH for neutralization. Calculate the percentage of nitrogen in the compound. (Atomic mass of N = 14)