1. Density of a Gas at STP

2. Density of a Gas at STP = 0.179 g/L
The densities for most substances are measured in units of g/cm3 or g/mL.
However, the density of gases is usually measured in units of g/L.
WHY?
Because the amount of gas in 1 cm3 is so small!
On Reference Table S, the density for helium is given as g/cm3 at 298K and kPa.
g/cm3 =
0.179 g/L

3. Density of a Gas at STP A 0.000446 L cube filled with 4.00 g copper
Copper cube
Is right here!
A L cube
filled with
4.00 g copper
at STP
A 22.4 L balloon filled
with 4.00 g helium gas
at STP

4. Density of a Gas at STP
Ex. (1) What is the density of a gas with a mass of g and a volume of 5.00 L? d = m V X =
6.45 g
5.00 L X =
1.29 g/L

5. Density of a Gas at STP
Ex. (2) What is the density of Xe gas (in g/cm3) at K and kPa? d = m V d =
g/cm3

6. Density of a Gas at STP
Ex. (3) What would be the volume of g of methane gas (d = g/L) at STP? d = m V
0.716 g/L =
3.926 g 1 X X =
5.48 L

7. Density of a Gas at STP
Ex. (4) What is the mass (in grams) of 112 cm3 of argon gas at 298 K and kPa? d = m V
g/cm3 = X 1
112 cm3 X =
0.183 g