Question

0.156 gram of an organic compound on Kjeldahl's analysis produced NH, which was absorbed in 60.25- mL of 0.05 MH2SO4. The acid left required 33 mL of M 20 NaOH for neutralisation. Calculate the percentage of nitrogen in the compound. ​

Answer 1

$\huge\bf\underline{\underline{\pink{A}\orange{N}\blue{S}\red{W}\green{E} \purple{R}}}★$

Mass of organic compound = 0.50 g

60 mL of 0.5 M solution of NaOH is required by residual acid for neutralisation 

⇒ 60 mL of 0.5 M solution of NaOH = 260 mL of 0.5M H2SO4 = 30mL of 0.5M H2SO4

∴ Acid consumed in absorption of evolved ammonia is (50-30)mL = 20mL

Again, 20mL of 0.5M H2SO4 = 40mL of 0.5M NH3

Since 1000mL of 1M NH3 contains 14g of nitrogen,

∴ 40mL of 0.5M NH3 will contain = 100014×40×0.5 = 0.28g of N

Therefore, percentage of N in 0.50g of organic compound = 0.500.28×100=56%

Hence, the correct answer is 56%.