Question

Ammonia contains 82.35% of nitrogen and 17.65% of hydrogen. Water contains 88.90% of oxygen and 11.10% of hydrogen. Nitrogen trioxide contains 63.15% of oxygen and 36.85% of nitrogen. Show that these data illustrate the law of reciprocal proportions.

Answer 1

A five litre flask contains 3.5g of nitrogen 3.0g of hydrogen and 8.0g of oxygen at 27c find the total pressure exerted by the mixture of these gasesA five litre flask contains 3.5g of nitrogen 3.0g of hydrogen and 8.0g of oxygen at 27c find the total pressure exerted by the mixture of these gasesA five litre flask contains 3.5g of nitrogen 3.0g of hydrogen and 8.0g of oxygen at 27c find the total pressure exerted by the mixture of these gases

Answer 2

Given,

In Ammonia:  

Nitrogen = 82.35%; Hydrogen = 17.65%  

That is, in Ammonia ${ NH }_{ 3 }$, 17.65 g of H combines with 82.35 g of N

Therefore, 1 g of Hydrogen combines with Nitrogen $=\quad \frac { 82.35 }{ 17.65 } \quad g\quad =\quad 4.67\quad g$

Given,  

In Water:  

Oxygen = 88.90%; Hydrogen = 11.10%

That is, in Water ${ H }_{ 2 }O$, 11.10 g of H combines with 88.90 g of N

Therefore, 1 g of Hydrogen combines with Oxygen $=\quad \frac { 88.90 }{ 11.10 } \quad g\quad =\quad 8.01\quad g$

Ratio of weights of Nitrogen and Oxygen which combine with the fixed weights 1 g of Hydrogen = 4.67 : 8.01

= 1 : 1.72

Given,

In Nitrogen trioxide:

Oygen = 63.15%; Nitrogen = 36.85%

That is, in Nitrogen trioxide ${ N }_{ 2 }{ O }_{ 3 }$,

Ratio of weights of Nitrogen and Oxygen which combine with each other  

= 36.85 : 63.15

= 1 : 1.72

Thus, the "law of reciprocal proportions" is illustrated since the ratios are same.