Question

Why is Dalton's Law Important?

Answer 1

Dalton's Law:

1. Dalton's law states that, “The sum of partial pressures of individual gases is equal to the total pressure of the gas mixture (mixture of non-reacting gases).”
2. Mathematically it can be represented as, $P=\sum _i{P}_i=P_1+P_2+P_3+\cdots +P_n$, where $P$ is the pressure of mixture and $P_1,P_2,P_3,\dots P_n$ is the pressure of $n$ number of gases.

Importance of Dalton's law :

1. In a gas mixture, if we know the mole fraction of individual gases and the overall pressure of the gas mixture then the partial pressure of individual gases can be calculated using the mole fraction formula $X_i=\frac{P_i}{P_{total}}=\frac{V_i}{V_{total}}=\frac{n_i}{n_{total}}$, where $X_i$ is the mole fraction of gas $i$, $P$ is pressure, $V$ is volume and $n$ is number of moles. Hence, it is used to calculate pressure, volume and number of moles of each gas.
2. Since gases are mostly collected over water, they contain water vapor, which exerts a pressure known as ‘aqueous tension’. By the application of Dalton's law, we can calculate the pressure of a dry gas by subtracting the aqueous tension from the total pressure of the moist gas, $P_{dry}=P_{moist}-aqueoustension$.
3. Dalton's law is used in 'Scuba tank'. The air inside it is carefully regulated to a specific mole fraction, which indicates that each of the gas present in the tank will have its own partial pressure.

Hence Dalton's law of partial pressure is important.