Question

A gaseous mixture contains 5.0 moles of nitrogen and 10.0 moles of helium. The total pressure in the container is 3 atmospheres. What is the partial pressure of the nitrogen?

• A. 1 atmosphere
• B. 0.5 atmospheres
• C. 3 atmospheres
• D. 2 atmospheres
• E. 15 atmospheres

Answer 1

The correct option is A 1 atmosphere

We know that the pressure of a gas in a container is directly proportional to the number of moles of gas present in the container.

$5$ moles of Nitrogen and $10$ moles of Helium are present. Thus, the total number of moles present is $(5+10)$, which is $15$ moles.

The total pressure in the container is $3$ atm.

Dalton's law of partial pressure says, that the total pressure exerted by a mixture of non-reacting gases is equal to the sum of the partial pressures exerted by individual gases.

Hence, the partial pressure of Nitrogen is $\frac{5}{15}\times 3$, where $5$ is the number of moles of Nitrogen present and $15$ is the total number of moles of both the gases present and $3$ atm is the total pressure.

Thus partial pressure of Nitrogen is $\frac{5}{15}\times 3=1atm$

Hence, option $A$ is correct.