Question

0.7 g of an organic compound was Kjeldahlized and
the liberated ammonia gas was absorbed in 100 mL of
0.1 N H2SO4. The excess of the acid required 10 mL of
0.2 N NaOH for complete neutralisation. Determine
the percentage of nitrogen in the organic compound​

Answer 1

Answer:

Explanation:

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 =  

2

60

​  

 mL of 0.5M H  

2

​  

SO  

4

​  

 = 30mL of 0.5M H  

2

​  

SO  

4

​  

 

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

Again, 20mL of 0.5M H  

2

​  

SO  

4

​  

 = 40mL of 0.5M NH  

3

​  

 

Since 1000mL of 1M NH  

3

​  

 contains 14g of nitrogen,

∴ 40mL of 0.5M NH  

3

​  

 will contain =  

1000

14×40

​  

×0.5 = 0.28g of N

Therefore, percentage of N in 0.50g of organic compound =  

0.50

0.28

​  

×100=56%

Hence, the correct answer is 56%.