STP Gas Calculations
One-step problems:
He
A balloon is filled with 3.78 L of
He gas at STP. How many moles
of helium atoms are inside?
Solution:
3.78 L He
1 mol
22.4 L
= 0.169 mol He
STP Gas Calculations
One-step problems:
CH4
A balloon is filled with 5.99 moles
of CH4 gas at STP. What is the
volume of the balloon in liters?
Solution:
5.99 mol CH4 22.4 L
1 mol
= 134 L CH4
STP Gas Calculations
One-step problems:
A balloon is filled with 36.2 liters
of Cl2 gas at STP. How many
moles of chlorine gas are inside?
Cl2
Solution:
36.2 L Cl2
1 mol
=
1.62
mol
Cl
2
22.4 L
STP Gas Calculations
One-step problems:
A balloon is filled with 0.333 mol
of Xe gas at STP. What is the
liter volume of xenon in the
balloon?
Xe
Solution:
0.333 mol Xe 22.4 L
1 mol
= 7.46 L Xe
STP Gas Calculations
One-step problems:
Ar
A balloon is filled with argon gas
at STP. What is the density of
the gas in the balloon?
Solution:
39.948 g Ar
1 mol
1 mol
22.4 L = 1.78 g/L Ar
STP Gas Calculations
One-step problems:
?
A balloon is filled with an
unidentified gas at STP. If its
density is 2.35 g/L, what is the
molar mass of this gas?
Solution:
2.35 g gas
1L
22.4 L
=
52.6
g/mol
1 mol
STP Gas Calculations
One-step problems:
C2H2
A balloon is filled with acetylene
gas at STP. What is the density
of the gas in the balloon?
Solution:
26.038 g C2H2 1 mol
=
1.16
g/L
C
H
2
2
1 mol
22.4 L
STP Gas Calculations
One-step problems:
?
A balloon is filled with a diatomic
gas at STP. If its density is
0.0900 g/L, what is the molar
mass of this gas?
What is the identity of this diatomic gas?
Solution:
Hydrogen H2
0.0900 g gas 22.4 L
=
2.02
g/mol
1L
1 mol
STP Gas Calculations
He
Two-step problems:
A balloon is filled with 300. liters of
helium gas at STP. What is the
mass in grams of this gas?
Solution:
Gas
Vol
mole
Mass
(g)
1 mol 4.0026 g He
300. L He
= 53.6 g He
22.4 L
1 mol
STP Gas Calculations
N2
Two-step problems:
A balloon is filled with 122 grams of
nitrogen gas at STP. What is the
volume in liters of this balloon?
Solution:
122 g N2
Mass
(g)
mole
Gas
Vol
1 mol
22.4 L
= 97.6 L N2
28.0134 g N2 1 mol
STP Gas Calculations
H2
Two-step problems:
A balloon is filled with 487 liters of
hydrogen gas at STP. What is the
mass in grams of this gas?
Solution:
487 L H2
Gas
Vol
mole
Mass
(g)
1 mol 2.01588 g H2
= 43.8 g H2
22.4 L
1 mol
STP Gas Calculations
Ne
Two-step problems:
A balloon is filled with 349 grams of
neon gas at STP. What is the
volume in liters of this balloon?
Solution:
Mass
(g)
mole
Gas
Vol
1 mol
22.4 L
349 g Ne
= 387 L Ne
20.1797 g Ne 1 mol
STP Gas Calculations
Two-step problems:
Several balloons are filled with 8250
total liters of helium gas at STP. How
many total atoms of helium are
contained in all of the balloons?
Solution:
Gas
Vol
mole
Atoms
1 mol 6.02x1023 atoms
8250 L He
= 2.22x1026
22.4 L
1 mol
atoms
STP Gas Calculations
Two-step problems:
A balloon in the shape of Darth Vader’s
head is filled with 8.0x1028 molecules of
nitrogen gas at STP. What is the
volume in liters of this balloon?
Solution:
8.0x1028 molec.
1 mol
6.02x1023 molec.
Molecules
mole
Gas
Vol
22.4 L
= 3.0x106 L N2
1 mol
STP Gas Calculations
Two-step problems:
A sleeping balloon is filled
with 2.75 liters of carbon
dioxide gas at STP. How
many molecules are
contained the balloon?
Solution:
2.75 L CO2
Gas
Vol
mole
Molecules
1 mol 6.02x1023 molecules
= 7.39x1022
22.4 L
1 mol
molecules
STP Gas Calculations
Two-step problems:
A large yellow ducky balloon is
filled with 2.5x106 liters of air at
STP. What is the mass in grams of
the air if the average molar mass is
29 g/mol?
Solution:
2.5x106
Gas
Vol
mole
Mass
(g)
1 mol 29 g air
L air
= 3.24x106 g air
22.4 L 1 mol
STP Gas Calculations
Two-step problems:
The Goodyear Blimp is
filled with 5.74x106 liters
of He at STP. What is
the mass in grams of
this much He?
Solution:
5.74x106
Gas
Vol
mole
Mass
(g)
1 mol 4.0026 g He
L He
= 1.03x106 g He
22.4 L
1 mol
STP Gas Calculations
Two-step problems:
If the balloon at the left were filled with
4.5x1028 molecules of methane gas at
STP instead of air, what would be the
volume in liters?
Solution:
Molecules
mole
Gas
Vol
This sort of gives new meaning to the term
“air head” doesn’t it?
4.5x1028 molec.
1 mol
6.02x1023 molec.
22.4 L
= 1.7x106 L CH4
1 mol
STP Gas Calculations
One-step problems:
If this flying cow balloon
was filled with sulfur
dioxide gas at STP instead
of hot air, what would it’s
density be?
Solution:
64.064 g SO2
1 mol
1 mol
=
2.86
g/L
SO
2
22.4 L
STP Gas Calculations
One-step problems:
If these balloons are filled with
gas at STP and their density is
1.85 g/L, what is the molar
mass of this gas?
Solution:
1.85 g gas
1L
22.4 L
=
41.4
g/mol
1 mol
STP Gas Calculations
Two-step problems:
If this girl inhales all of the
helium from this balloon that
has a volume of 1.25 liters at
STP, how many atoms does
she inhale?
Solution:
1.25 L CO2
Gas
Vol
mole
Molecules
1 mol 6.02x1023 molecules
= 3.36x1022
22.4 L
1 mol
atoms of He
STP Gas Calculations
Two-step problems:
If this girl’s balloon is filled
with 4.0 liters of CO2 gas at
STP and someone popped
it with a pin, what mass in
grams would be released?
Solution:
4.0 L CO2
Gas
Vol
1 mol
22.4 L
mole
Mass
(g)
44.010 g CO2
= 7.86 g CO2
1 mol