Gases

STP tells us that 1 atmosphere is 273K. When we do the problems, we have to change the variables of temperture to Kelvin.

For equation PV=nRT, P is pressure(atm, kPa), V is volume(L), n is number of moles(mol), T is temperature(K) and R is a gas law constant. R is always constant and it has value of .0821(L atm)/(K mol).

The important thing that we hace to remember is that volume of 1mol He at stp is 22.4L.

I also learned that higher attitudes have less air pressure. And at a given T, lightest molecules move fastest and heaviest molecules move slowest.

Charles' Law abd Gay-Lussac's Law tell us that they are both directly proportional.

Equations for both Laws are V=kT and P-kT.

The combined gas law is P1V1/T1=P2V2/T2. They also have to use temperatures as in Kelvin, too. To change the Celcius to K, you just have to add 273 to the Celcius temperature and that will make you to have Kelvin.