Chemistry Question: Charles Law?

Question

I need help on how to get started with a homework problem. Here is the problem:

Temperature of hot air = 100 degrees celsius
Temperature of cold air = 0 degress celsius
Volum of water pulled into the flask(mL) = 214 mL
Maximum volume of water the flask will hold (mL) = 300 mL

What is the volume of air in the flask at the hot temperature?
What is the volume of air in the flask at the cold temperature?

I have looked in my school book but there is no information on how to do this. If someone could help me get started with this problem, it will be greatly appreciated. You do not need to do the problem for me, just tell me what I need to do. THANKS!!!

Answer 1

Let's assume that the flask is upside down in a water bath.
At 100 C, it contains some water (volume = x), and a volume of hot gas (VH). When cooled to 0 C, the volume of the gas decreases, and some water (214 mL) is pulled into the flask. The volume of the cool gas is now VC.

Some relationships to get you started:

VH - x = 300 mL
VH - VC = 214 mL

Charles' Law

VC / TC = VH / TH

or

TH /TC = VH / VC

Answer 2

For two sets of conditions, for change of temp only, use charles's with temps in Kelvin For two sets of conditions, for change of pressure only, use boyle's, units don't matter as long as they're both the same For one set of conditions (e.g. not two temps or two pressures), the Ideal gas law is used . You can also pick these out because they will have grams or moles in the problem. It can also be used for density problems with g/mL that you convert to moles/L so units cancel.