Return to Blog
Homepage
PCAT Chemical Processes – Gas Behavior
- by
- Oct 25, 2017
- PCAT Question of the Day
A 2 L sealed vessel contains 2 moles of nitrogen gas at 0oC. All of the following will decrease the pressure inside the vessel EXCEPT:
- nitrogen leaking out of the tank
- decreasing the temperature of the gas
- expanding the volume to 3 L
- replacing 1 mole of nitrogen gas for 1 mole of oxygen gas
Explanation
This question is testing your understanding of gas behavior according to the ideal gas law.
PV = nRT
When nitrogen leaks out of the tank, the moles of nitrogen, n, decreases. Since pressure is proportional to moles, decreasing the moles of gas will decrease the pressure making A incorrect. Since temperature is also proportional to pressure, a decrease in temperature will lower the pressure making B false. Pressure and volume are inversely related, which means that increasing the volume will result in a decrease in pressure. Therefore, C is not the correct answer, which leaves D as the correct answer. Exchanging 1 mole of nitrogen gas for 1 mole of oxygen changes the partial pressures within the system but has no effect on total pressure.
Related Post
Search the Blog
Free Consultation
Interested in our Online MCAT Course, One-on-One MCAT Tutoring or Med admissions packages? Set up a free consultation with one of our experienced Senior Student Advisors.
Schedule NowPopular Posts
-
-
-
-
-
MCAT Blog How to Review MCAT Full-Lengths
Free MCAT Practice Account
Need great MCAT practice?Get the most representative MCAT practice possible when you sign up for our free MCAT Account, which includes a half-length diagnostic exam and one of our full-length MCAT practice exams.
Learn More
Submit a Comment