Gas Question Boyle's Law

[Sophie522]

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One liter of nitrogen and one liter of carbon dioxide initially at one atmosphere pressyre are forced into a single 500 mL vessel. What is the new nirtogen pressure if the temperature remains unchanged?

A. 1 atm
B. 2 atm
C. 3 atm
D. 4 atm
E. 5 atm



Correct Answer: B

According to Boyle's Law, the pressure of a gas is inversely proportional to its volume. To have the volume, double the pressure. This is why the answer is B. However, does it not matter that you also have a liter of CO2 in the mixture? Thanks for your help.

 

[CANgnome]

it is asking for partial pressure, so you only consider nitrogen. If asking for the whole system, then it is 2x from doubling # moles and 2x from halving volume.

 

[Sophie522]

that is what i thought too (find the partial pressure of nitrogen), but the explanation in the book treats it as a whole system. even if i wanted to solve for partial pressure, i'm not given the moles to calculate a mole fraction and the total pressure of the system, right?

-->According to Boyle's Law, the pressure of a gas is inversely proportional to its volume. To have the volume, double the pressure. This is why the answer is B.

confusing.

 

[CANgnome]

at STP, 1moles exist in 22.4L, 1atm, 0degrees celcius, so there is one way to calculate #moles :x