Question

Which mixture of gases at room temperature does not obey Dalton’s law of partial pressure?
(a)- $N{O}_2\text{ and }{O}_2$
(b)- $N{H}_3\text{ and }HCl$
(c)- $CO\text{ and }C{O}_2$
(d)- $S{O}_2\text{ and }S{O}_3$

Answer 1

Hint: Dalton’s law of partial pressure says that the total pressure of the gaseous mixture is equal to the partial pressure of all the gases present in the mixture. So, the gases must not react with each other. Hence, find the option in which the gases react with each other.

Complete step by step answer:
The various gas laws deal only with the pressure, volume, and temperature of a single gas. However, if two or more chemically non-reacting gases are enclosed in the same vessel, the pressure exerted by the mixture was first studied in 1807 by John Dalton. He observed the gases and put forward the result which is known as Dalton's Law of Partial Pressure:
“If two or more gases which chemically do not react with each other are enclosed in a vessel then the total pressure is equal to the sum of the partial pressure of each gas would exert when present alone in the vessel present at the same temperature"
Let a vessel contain n number of gases. The total pressure of the gases in the vessel is P. The partial pressure of the gases are$p_1,p_2,p_3........p_n$. So, according to
Dalton's law:
$P=p_1\text{+ }{p}_2\text{+ }{p}_3+........+p_n$

The condition is that the gases must not react with each other.
From the above options given $N{H}_3\text{ and }HCl$ react with each other, therefore, they will not obey Dalton's Law of Partial Pressure.
So, the correct answer is $N{H}_3\text{ and }HCl$
So, the correct answer is “Option B”.

Note: Dalton's Law of Partial Pressure is used to calculate the pressure of dry gas. The formula used is: $P_{drygas}=P_{moistgas}-Aqueoustension$. It is also used to calculate the partial pressure of any component in the mixture. The formula used is $\text{Partial Pressure of A = Mole fraction of A x Total pressure}$.