GS-1 Physical Sciences Question 25

[dsoofer5383]

If the T has increased, how can the P decrease?
(PV=nRT)

[mcat_premed3832]

PV = nRT is the ideal gas equation. All the parameters relate to a gas. And really, it is only to be used in ideal conditions (when the pressure is low and temperature is high).

This problem is about a solution being compared to a solvent (pure water). The ideal gas equation does not apply.

If you really wanted to use the ideal gas equation, then you would have to focus exclusively on the gas (the vapor); in which case you can say, as the temperature of the vapor increases, then the pressure in a closed container related to the vapor must also increase if all other parameters remain constant (which should be true in a closed container).

Colligative properties are commonly tested on the MCAT.

[mohsinalam5969]

The relationship depends on the gas being compressed. For those gases that can be treated as perfect gases, the perfect gas equations can be used. For those gases that cannot be treated as perfect gases, real gas relationships must be used.
In this case a solution being compared to a solvent (pure water). The ideal gas equation does not apply.
so
PV = nRT
no longer remains true for the present case.

hope this is helpful