Question

An apparatus consists of a 3 L flask containing nitrogen gas at 17◦C and 822 kPa, joined by a valve to a 10 L flask containing argon gas at 17◦C and 59 kPa. The valve is opened and the gases mix. a) What is the partial pressure of nitrogen after mixing?
b) What is the partial pressure of argon aftermixing?
c) What is the total pressure of the gas mixture?

Answer 1

Answer:

a) 189.7 kPa

b) 45.4 kPa

c) 235 kPa

Explanation:

After the mixture, the temperature must remain the same, because both gases are at 17°C. Besides, the gases will not react because both nitrogen and argon are non-reactive. So, the partial pressure can be calculated by Boyle's Law:

P1*V1 = P2*V2

Where P is the pressure, V is the volume, 1 is the initial state, and 2 the final state.

When the valve is opened, the gases mix and occupy all the two vases. So, V2 = 13 L.

a) For nitrogen, P1 = 822 kPa, V1 = 3L, V2 = 13 L

822*3 = P2*13

P2 = 189.7 kPa

b) For argon, P1 = 59 kPa, V1 = 10 L, V2 = 13 L

59*10 = P2*13

P2 = 45.4 kPa

c) By Dalton's law, the total pressure of a gas mixture is the sum of the partial pressures of the components, so:

P = 189.7 + 45.4

P = 235 kPa