Answer to Question #139057 in General Chemistry for Isabel

Question

Daltons law of partial pressures

Answer 1

Dalton’s law of partial pressures is a gas law which states that the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures exerted by each individual gas in the mixture. For example, the total pressure exerted by a mixture of two gases A and B is equal to the sum of the individual partial pressures exerted by gas A and gas B (as illustrated below).

Dalton’s Law Formula

Dalton’s law of partial pressures can be mathematically expressed as follows:

P_total = ∑ⁿ_i=1p_i(or) P_total = P₁ + P₂ + P₃ + …. + P_n

Where,

• P_total is the total pressure exerted by the mixture of gases
• P₁, P₂,…, P_n are the partial pressures of the gases 1, 2,…, ‘n’ in the mixture of ‘n’ gases.

Expressing Partial Pressures in Terms of Mole Fraction

The mole fraction of a specific gas in a mixture of gases is equal to the ratio of the partial pressure of that gas to the total pressure exerted by the gaseous mixture. This mole fraction can also be used to calculate the total number of moles of a constituent gas when the total number of moles in the mixture is known. Furthermore, the volume occupied by a specific gas in a mixture can also be calculated with this mole fraction with the help of the equation provided below.

of the equation provided below.

X_i=P_i/P_total=V_i/V_total=n_i/n_total

Where X_i is the mole fraction of a gas ‘i’ in a mixture of ‘n’ gases, ‘n’ denotes the number of moles, ‘P’ denotes pressure, and ‘V’ denotes volume.