Untitled - Kelly Walsh High School

Gases 89
The larger the gas particle, the more concentrated, and the stronger the intermolecular
forces of the gas, the more deviation from the ideal gas equation one
can expect and the more useful the van der Waals equation becomes.
5-5 Utterly Confused About Gas
Law Problems
Quick Tip
Quick Tip
Gas law problems, like all problems, begin with isolating the variables and the
unknown from the question. The usual suspects in gas law problems are pressure,
volume, temperature, and moles. You will need to deal with at least two
of these properties in every problem.
If you have a gas at a certain set of volume/temperature/pressure conditions and
at least some of the conditions change, then you will probably be using the combined
gas equation. If moles of gas are involved, the ideal gas equation will probably
be necessary
We will begin with a two variable problem. A sample of a gas has a volume of
5.00 L at 25C. What temperature, in C, is necessary to increase the volume of
the gas to 7.50 L? We start by separating the numbers (and associated units) and
the actual question from the remainder of the problem. Be very Careful! that
the variables starting together stay together. Each column in the following table
contains variables that began together.
V 5.00 L V 7.50 L
T 25C 298 K T ?C
When working gas law problems all temperatures used in the calculations must
be in Kelvin units. You should change any other temperature units to Kelvin as
soon as possible to minimize forgetting to do so later.