A2L Item 114
- Description: Identify the final pressure after an ideal gas undergoes a free expansion.
- Goal: Problem solving with the ideal gas law
- Source: UMPERG-ctqpe184
- Keywords: Ideal Gas, Thermodynamics
The question for students:
Two moles of an ideal gas fill volume V = 10 liters at pressure P = 2.4 atm. The gas is thermally insulated from the surroundings. A membrane is broken which allows the gas to expand into the new volume which is 3 times as large as the old volume. The new pressure is:
- .4 atm
- .8 atm
- 1.2 atm
- 1.6 atm
- 2.4 atm
- None of the above
- Cannot be determined
Commentary for teachers:
Answer
(2) Some students may wonder about the applicability of the ideal gas law for free expansion. Some may respond (7) thinking that since gas cools as it expands, they do not know what the final temperature is and cannot, therefore, use the ideal gas law.