Question

To which of the following the Dalton’s law of partial pressure is not applicable?
A) ${H_2}$ and $He$
B) $N{H_3}$ and $HCl$
C) ${N_2}$ and ${H_2}$
D) ${N_2}$ and ${O_2}$

Answer 1

Hint: Dalton's law of partial pressures states that the total pressure of a gas mixture is the summation of partial pressures of its components. It can be given as,
${{\rm{P}}_{\rm{T}}} = {{\rm{P}}_{\rm{1}}} + {{\rm{P}}_{\rm{2}}} + {{\rm{P}}_3} + ........$
Here, ${{\rm{P}}_{\rm{T}}}$implies the total pressure of the gas and ${{\rm{P}}_2}$, ${{\rm{P}}_2}$ and ${{\rm{P}}_3}$are the partial pressures of its components 1, 2,3 etc.

Complete step by step answer:
Dalton's law of partial pressure is applicable when the component of the gases in a mixture does not react with each other. It is also not applicable when the mixture of reacting gases is at room temperature for. Dalton's law of partial pressure is not applicable when a gas reacts under experimental conditions. As the $N{H_3}$ and $HCl$ reacts under the ordinary conditions, Dalton's law of partial pressure is not applicable to this mixture.

So, the correct answer is “Option b”.

Additional Information:
The mole fraction of a gas in a mixture of gases is equal to the ratio of the partial pressure of the gas to that of the total pressure exerted by the gas mixture. We can use this mole fraction to calculate the total number of moles of a constituent gas when we know the total number of moles in the mixture. We can also calculate the volume occupied by a gas in a mixture using this mole fraction using the following equation:
${{\rm{X}}_{\rm{i}}} = {{\rm{P}}_{\rm{i}}}{{\rm{P}}_{{\rm{total}}}} = {{\rm{V}}_{\rm{i}}}{{\rm{V}}_{{\rm{total}}}} = {{\rm{n}}_{\rm{i}}}{{\rm{n}}_{{\rm{total}}}}$
Here,${{\rm{X}}_{\rm{i}}}$ is the mole fraction of a gas ‘${\rm{i}}$’ in a mixture of ‘${\rm{n}}$’ gases, ‘${\rm{n}}$’ is the number of moles, ‘${\rm{P}}$is the pressure, and ${\rm{V}}$ denotes volume.

Note:
It is important to note that Dalton's law of partial pressures is applicable to a mixture, when the component of the gases in a mixture does not react with each other.