Question

Consider the gaseous reaction: A(g) + B(g) → AB(g) A mixture of 0.04 mol of gas A and 0.1 mole of gas B was allowed to react at 300 K in a 1 L sealed container. At the end of the reaction, what is the total pressure of the mixture?

Answer 1

The total pressure of the mixture is 2.5 atm.

Step-by-step explanation:

According to Dalton´s law of partial pressures, the total pressure of the mixture is the sum of the partial pressures of each gas.

From the chemical equation, we know that 1 mol of A reacts with 1 mol of B to produce 1 mol of AB. We have only 0.04 mol of gas A, then, only 0.04 mol of AB will be produced when reacting with 0.04 mol of B. 0.06 mol of B will remain without reacting.

After the reaction, there will be 0.04 mol of AB and 0.06 mol of B.

The pressure of AB can be calculated as follows:

PAB = n*R*T / V

Where:

PAB = partial pressure of gas AB.

n = number of mole of AB.

R = gas constant = 0.082 l atm / K mol

T = temperature

V = volume

Then:

PAB = 0.04 mol * 0.082 (l atm / K mol) * 300 K / 1 l = 0.98 atm.

In the same way, the partial pressure of B can be calculated:

PB = 0.06 mol * 0.082 (l atm / K mol) * 300 K / 1 l = 1.5 atm.

The total pressure (Pt) is then:

Pt = PAB + PB = 0.98 atm + 1.5 atm = 2.5 atm