Calculating Total Internal Energy for a Monatomic Gas at Constant Pressure

[john mcgrain]

Homework Statement

There is a monatomic gas held at a constant pressure of P = 1.48-atm, it also has a molar mass M = 16-g/mol and density ρ =1.9 × 10-3-g·cm-3. Find the total internal energy of 1-mol of this gas.

Homework Equations

U = Q + W
E = nCvT
PV = nRT

The Attempt at a Solution

I have tried E = 3/2nRdT but I am unsure as to how I could use molar mass and density to find anything that can be subbed into the equations. I tried dividing M and ρ cm-3/mol but I'm not sure were to go from there.

 

[TSny]

Welcome to PF

I have tried E = 3/2nRdT

What does "d" stand for here?

I tried dividing M and ρ cm-3/mol .

OK. Watch the units, they're not quite correct here. With the units corrected, what useful information is this giving you?

 

[john mcgrain]

Welcome to PF
What does "d" stand for here?

OK. Watch the units, they're not quite correct here. With the units corrected, what useful information is this giving you?

The d is for delta. As in delta T change in temperature. When dividing M and ρ it seems as though grams cancels out and you're left with 1/cm-3*mol. If i instead divide ρ by M we are left with cm-3*mol which is V x n. I don't see where this can be put into the formula though, is there a formula I'm missing?

 

[TSny]

The d is for delta. As in delta T change in temperature.

Why do you want to use a temperature change? Are you trying to determine a change in energy?

When dividing M and ρ it seems as though grams cancels out and you're left with 1/cm-3*mol.

OK. Note the negative power on cm. What would the units look like if you rewrote it with the cm part in the numerator?

 

[Chestermiller]

Have you considered using the ideal gas law to get the temperature? From the ideal gas law, how is mass density $\rho$ related to P, M, R, and T?