Gas Laws

blackjack18

If 0.5 mol of nitrigen gas occupies a volume of 11.2 L at 0 degrees Celsius, what volume will 2 mol of nitrogen gas occupy at the same temperature and pressure?

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LowlyPion

Homework Helper
If 0.5 mol of nitrigen gas occupies a volume of 11.2 L at 0 degrees Celsius, what volume will 2 mol of nitrogen gas occupy at the same temperature and pressure?
Welcome to PF.

What is your thinking about how to approach the problem?

blackjack18

all i really need help with is the pressure... i have the formula for the problem i think (boyle's law) but i do not know the what the pressure is...

LowlyPion

Homework Helper
all i really need help with is the pressure... i have the formula for the problem i think (boyle's law) but i do not know the what the pressure is...
What happens when you divide one equation by the other?

blackjack18

i dont know...boyles law states P x V = constant....and i dont know what the pressure is

blackjack18

is 44.8 L/mol is the answer?

nicksauce

Homework Helper
I would almost agree, but it asks for the volume it occupies, not the volume per mol. I get 44.8 L as an answer.

LowlyPion

Homework Helper
is 44.8 L/mol is the answer?
That's what it looks like except drop the /mol.

nicksauce

Homework Helper
i dont know...boyles law states P x V = constant....and i dont know what the pressure is
I don't think Boyle's law applies if the amount of material changes. I would think the ideal gas law should be applied instead. PV=nRT (n = number of moles, R = gas constant, T = temperature).

blackjack18

alrighty, thanks...

blackjack18

Should Boyle's Law be used in this problem, since the temperature remains constant:

What is the volume of an ideal gas at 1 atm, 12 L, and 25 degrees Celsius if the pressure is decreased to 0.8 atm at 25 degrees Celsius?

nicksauce

Homework Helper
Yes.

May I recommend that instead of memorizing or search for different laws for different problems you could simply ALWAYS apply the Ideal Gas Law since ,Charles', Boyles' and Avagadro's Laws are simply special cases of the I.G. Law.

LowlyPion

Homework Helper
Should Boyle's Law be used in this problem, since the temperature remains constant:

What is the volume of an ideal gas at 1 atm, 12 L, and 25 degrees Celsius if the pressure is decreased to 0.8 atm at 25 degrees Celsius?
Strictly speaking you should consider using the Ideal Gas Law PV = nRT.

To find unknowns in situations that some things change and others don't, then divide the two equations such that

P1V1/P2V2 = n1R1T1/n2R2T2

Just cross out the things that don't change between 1 and 2.

blackjack18

is the answer v2=15 L?

LowlyPion

Homework Helper
is the answer v2=15 L?
You've already posted the answer. Are you answering another problem?

blackjack18

yes, is that the answer to the following: What is the volume of an ideal gas at 1 atm, 12 L, and 25 degrees Celsius if the pressure is decreased to 0.8 atm at 25 degrees Celsius?

blackjack18

yes, is that the answer to the following: What is the volume of an ideal gas at 1 atm, 12 L, and 25 degrees Celsius if the pressure is decreased to 0.8 atm at 25 degrees Celsius?

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