# AP Chemistry

posted by
**Janice** on
.

The normal boiling points of CO and SO2 are -192 degrees C and -10 degrees C, respectively

A) At 25 degrees C and 1 atm, which gas would you expect to have a molar volume closest to the ideal value?

B) If you reduce the deviation from ideal gas behavior, in what direction would you change the temperature? The pressure?

Two questions:

How do you calculate molar volume?

For B), would the pressure stay the same since it's 1 atm and molar volume deviates more as it approaches more extreme temperatures/pressures?

A) PV=nRT

T is the same. R is the same. n is the same. P is the same. Volume is the only variable that can change.

Real gases deviate from ideal behavior most at low temperatures or extremely high pressure. These deviations occur because the volume of the gas is not negligible AND because the attraction between molecules is not negligible. Given that CO and SO2 both have dipole moments, that CO is smaller than SO2, and that SO2 is nearer its liquification temperature than CO, which do you think?

B)Remember to stay away from low T and high P.

To calculate molar volume, use the gas equation, PV = nRT or is that obvious and you had something else in mind.

I don't understand your question under B. **Perhaps another tutor will**

"To calculate molar volume, use the gas equation, PV = nRT or is that obvious and you had something else in mind."

Well what I'm confused about in this case is that since T, R, and P are the same for both CO2 and SO2, does that mean that the volumes are the same?

For an ideal gas, yes. For a real gas, no. For real gases, look up a and b for each of the gases and use the van der Waals equation of state (unless you are determining all this from an experiment).