Question

The total pressure of a mixture of two gases is equal to:
A. Sum of their partial pressures
B. The difference in partial pressures
C. The product of partial pressures
D. The ratio of partial pressures

Answer 1

Gases have the property to exert pressure; this property is used when two gases are mixed together. The pressure exerted by each gas alone is called the partial pressure of a gas, this partial pressure is directly proportional to mole fraction. The total pressure can be derived by Dalton's theory of partial pressure.

Complete answer:
The mixture of a gas contains various gases, the pressure exerted by each gas individually in that mixture is known as partial pressure of that gas. For a mixture of a gas, Dalton gave a law that calculated the total pressure of the mixture of the gas.
According to Dalton's law of partial pressure, the total pressure of a gas having a mixture of various gases is equal to the sum of the partial pressures exerted by each gas. For instance a mixture has gas X and Y then the total pressure will be the sum of partial pressures of X and Y.
This can be illustrated as:
${{P}_{total}}={{P}_{1}}+{{P}_{2}}+{{P}_{3}}........+{{P}_{n}}$ , where n is the number of gases.
So, the total pressure of a mixture of two gases is equal to the sum of their partial pressures.

So option A is correct.

Note:
The pressure of any gas is the product of partial pressure and mole fraction of that gas, or the partial pressure of a gas is the product of the total pressure and the mole fraction of that gas. Mole fraction of any gas is the number of moles of that gas upon the total number of moles of all the gases.