PCAT Chemical Processes – Ideal Gas Law
 by
 Oct 25, 2017
 PCAT Question of the Day
A container with a pressure of 3 atm occupies a volume of 11.2 L at 273 K. How many moles of gas are present in the container?
A) 0.5 moles
B) 1 mole
C) 1.5 moles
D) 3 moles
Explanation
This question is testing your understanding of the ideal gas law, PV = nRT, and standard temperature and pressure (STP) conditions. To determine the number of moles of gas occupied under the conditions specified in this question, you must rearrange the ideal gas law to solve for n in terms of pressure, volume, temperature and the constant R.
n = PV/RT
At STP (P = 1 atm, T = 273 K), 1 mole of gas (n = 1) occupies a volume of 22.4 L. Therefore, the ratio PV/RT = n = (1)(22.4)/(0.082)(273) = 1. Since in this problem, the ratio PV/RT = n = (3)(11.2)/(0.082)(273) = 1.5, the number of moles of gas is equal to 1.5 making C the correct answer.
Search the Blog
Free Consultation
Interested in our Online MCAT Course or one of our OneonOne MCAT Tutoring packages? Set up a free consultation with one of our experienced Academic Managers!
Schedule NowPopular Posts

MCAT Blog How to Review MCAT FullLengths
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 halflength diagnostic exam and one of our fulllength MCAT practice exams.
Learn More
Submit a Comment