Chemistry homework question

Question

The pressure of a sample of argon gas was increased from  to  at constant temperature. If the final volume of the argon sample was  what was the initial volume of the argon sample? Assume ideal behavior.

Answer 1

Hello, Brianna,

There are no pressures indicated in the question. But I'll explain the technique for doing the calculation.

The ideal gas law is PV = nRT, where P is pressure. V is volume. n is moles, T is the temperature in K, and R is the gas constant.

When dealing with the same gas sample, the gas law can be written to show the difference in two states (1 for initial, and 2 for final).

P1V1/T1 = P2V2/T2

The n(moles) and R(the gas constant) cancel out. In your problem, the temperature is also constant, so T1 = T2, and they also cancel out, leaving:

P1V1 = P2V2

You have V1, and presumably P1 and P2, so rearrange the equation to:

P1V1/P2 = V2 and put in your data to calculate V2. Make sure the pressures are in the same units (e.g., atm, mmHg, torr, etc.). This basically says is you double the pressure, you'll halve the volume.

The term "ideal" gas law comes from the need to assume that the gasses being measured do not interact with each other and are completely free to move in the gas phase.

I hope this helps,

Bob