Rate of Pressure Change with Temperature in Ideal Gas Law

[cmajor47]

Homework Statement

According to the ideal gas law, the pressure, temperature, and volume of a gas are related by PV=kT, where k is a constant. Find the rate of change of pressure (pounds per square inch) with respect to temperature when the temperature is 300^{o}K if the volume is kept fixed at 100 cubic inches.

Homework Equations

The Attempt at a Solution

PV=kT
P=V^-1kT
P=100^-1kT
\frac{dP}{dT}=100^-1k

I don't know how to figure this out. We were given the answer, -.01 psi/^{o}K but I don't know how to get to this with the k there.

 

[quantumdude]

k is Boltzmann's constant.

 

[Redbelly98]

This is weird. You're given information (T=300K) which is not necessary for calculating ∂P/∂T, and not given enough information to figure out what k is.

Moreover, pressure should increase as the gas is heated up. Yet "the answer" is a negative quantity!

Something is definitely not right here.

 

[Redbelly98]

k is Boltzmann's constant.

That's what I thought when I first saw the problem. But where is the number of gas molecules in PV=kT? Either that equation was not written correctly, or k really is just "a constant".