1. Avogadro’s Law and Molar Volume

2. Recap
So far we have manipulated 3 variables: ______, _______, and _______
The one variable that has remained constant is ________
What happens when we change the quantity (i.e. number of moles) of a gas?

3. Predict…
2 L of H2(g)
1 L of O2(g)
___ L of ____ (g)

4. The Law of Combining Volumes
Gay-Lussac’s “real” law
“When temperature and pressure remain constant, the volumes of gaseous reactants and products are always in simple whole number ratios”
STOICH!

5. Avogadro’s Law
The volume of a gas is directly proportional to the amount of gas, when temperature and pressure remain constant.
V  n
V = kn
V = k n
V1 = V2
n1 n2
Molar Volume:
If equal volumes of any gas contain the same number of particles (at constant T & P)…
Then one mole of any gas should occupy the same volume (under defined conditions)

6. Consider the following gas densities at STP:
Density
(g/L)
Molar Mass
(g/mol)
Molar Volume (L/mol) O2
1.429
32.00
22.39 He
0.1785
4.003
22.43
NH3
0.7621
17.03
22.35 H2
2.016
CH4
0.7161
16.04
22.40
At STP (O˚C, kPa) one mole of any gas occupies 22.4 L
At SATP (25˚C, 100 kPa) one mole of any gas occupies 24.8 L

7. Homework
Read p
P. 468 #1-5
P.471 #7-12
P. 474 #2-6