1. Moles, volume and density

2. Calculate the volume of a given mass of a gaseous substance from its density at a given temperature and pressure.
Include: molar volume calculation
Solve problems requiring interconversions between moles, mass, volume, and number of particles.
Additional KEY Terms
STP

3. Avogardo ( )
Avogadro’s Hypothesis - any sample of any gas at the same temperature and pressure will contain the same number of particles.

4. Chemists use a standard temperature and pressure, STP, to measure gas volumes.
0°C and kPa
At STP:
The volume of 1 mole of ANY GAS is 22.4 L.
22.4 L/mol is known as molar volume.
The MASS of 22.4 L of any gas is equal to the
molar mass for that gas.

5. How many moles are in 50.0 L of Fluorine gas at
STP?
F2 = 36.0 g/mol
50.0 L
22.4 L
1 mol
= mol

6. What is the STP volume of 10.0 g of Methane gas?
CH4 = 16.0 g/mol
10.0 g
16.0 g
1 mol
1 mol
22.4 L
= L

7. Density: A physical property that describes the mass per unit volume of a substance.
grams (g) per litre
grams per mL (or cm3)

8. Calculate the volume, in litres, of one mole of
ammonia (NH3) at room temperature if the density
is g/L.
NH3 = 17.0 g/mol
1 mol
1 mol
17. 0 g
0.696 g
1 L
= L

9. Calculate the volume, in litres, of two moles of carbon dioxide, at room temperature, when the density is 1.80 g/L.
CO2 = 44.0 g/mol
2 mol
1 mol
44. 0 g
1.80 g
1 L
= L

11. · STP: 0°C and kPa (1 atm)
· At STP, the molar volume of any gas is 22.4 L
· Molar mass = total grams in 1 mole (g/mol)
· 1 mole = 6.02 x 1023 particles (Avogadro)
· density of a substance = mass per volume (g/L)
* All roads lead to moles (convert to moles first).

12. CAN YOU / HAVE YOU?
Calculate the volume of a given mass of a gaseous substance from its density at a given temperature and pressure.
Include: molar volume calculation
Solve problems requiring interconversions between moles, mass, volume, and number of particles.
Additional KEY Terms
STP