1. DO NOW: Complete on the BACK of the NOTES!
The volume of a gas is 550 mL at 960 mm Hg and oC. What volume would the pressure of the gas be 830 mm Hg if the temperature is reduced to 150.0oC?
At what temperature (in oC) would a gas have a volume of 13.5 L at a pressure of atm, if it had a volume of 17.8 L at a pressure of atm and a temperature of 28.0oC?

2. Notes
Unit: Gas Laws
Ideal Gas Law

3. After today you will be able to…
Explain what an ideal gas is
Calculate an unknown pressure, temperature, volume, or amount of gas using the ideal gas law equation

4. Ideal Gases
Ideal gases are gases that are said to follow all assumptions of kinetic molecular theory.
An ideal gas is also considered to conform to all gas laws.

5. Ideal Gases
Up until now we have only changed variables such as pressure, volume, and temperature of a gas.
In each of these cases the amount of gas was assumed constant.
The combined gas law can be modified to include the amount of gas by including the variable, n.

6. Ideal Gas Law
This gas law relates the amount of gas (in moles) to the volume it would occupy at a particular temperature and pressure.

7. Ideal Gas Law PV=nRT STOP! It is often called
the “picky” law! The units must be what you see here!
Where, P= pressure (atm) V= volume (L) n= moles (mol) R= L·atm/mol·K T= temperature (K)
PV=nRT
R is called the Ideal Gas Constant (it has multiple values, but for our purposes we will only use this one).

8. Ideal Gas Law Example PV=nRT
At what pressure would mol of a gas occupy 6.84L at 89°C? P= V= n= R= T=
PV=nRT ?
(P)
(6.84L) =
(0.212mol)
(0.0821)
(362K)
6.84L P
0.212mol =
0.92atm
0.0821L·atm/mol·K
89°C + 273= 362K

9. Ideal Gas Law Example PV=nRT
At what temperature would 52.3g of methane (CH4) gas occupy 65.7L at 184kPa? P= V= n= R= T=
PV=nRT
1 atm
184kPa x =
1.82 atm
101.3kPa
65.7L
1 mol CH4
52.3gCH4 x =
3.26 mol CH4
16.05gCH4
0.0821L·atm/mol·K
(1.82atm)
(65.7L) =
(3.26mol)
(0.0821)
(T) ? T =
447K

10. Questions? Complete WS