dcasey

12-05-17 KMT and GAS laws 1

December 05, 2017

Date: December 05, 2017

Before you go you should know what the kinetic molecular theory is and how to use Boyle's, Charles's, and Gay-Lusac's Laws to solve problems.

Warm-Up: Go to you 2007 Sol (it was downloaded from

my website already) and do questions 7-12.

62.5

MgCl2

22p 28n 22e

dcasey

12-05-17 KMT and GAS laws 2

December 05, 2017

f,d,f

dcasey

12-05-17 KMT and GAS laws 3

December 05, 2017

The Gas LawsThese will describe HOW gases behave.Can be predicted by the theory.Amount of change can be calculated with mathematical equations.Ideal GasesWe are going to assume the gases behave “ideally”- obeys the Gas Laws under all temp. and pres.An ideal gas does not really exist, but it makes the math easier and is a close approximation.Particles have no volume.No attractive forces.Ideal GasesThere are no gases for which this is true; however,Real gases behave this way at high temperature and low pressure

Ideal Gases don’t exist Molecules do take up space There are attractive forces otherwise there would be no liquids formedReal Gases behave like Ideal gases ...When the molecules are far apartThe molecules do not take up as big a percentage of the spaceWe can ignore their volume.This is at low pressure

When molecules are moving fast = high temperatureCollisions are harder and faster.Molecules are not next to each other very long.Attractive forces can’t play a role.

dcasey

12-05-17 KMT and GAS laws 4

December 05, 2017

1. Boyle’s LawAt a constant temperature, gas pressure and volume are inversely related.As one goes up the other goes down

Formula to use: P1 x V1 = P2 x V2

2. Charles’s LawThe volume of a gas is directly proportional to the Kelvin temperature, if the pressure is held constant.Formula to use:

3. Gay-Lussac’s LawThe temperature and the pressure of a gas are directly related, at constant volume.Formula to use:

V1 = V2

T1 T2

P1 = P2

T1 T2

4. Combined Gas LawThe Combined Gas Law deals with the situation where only the number of molecules stays constant.

Formula: (P1x V1)= (P2x V2)

T1 T2

This lets us figure out one thing when two of the others change.