Practice Problems
Ideal Gas Law
Directions:
On this worksheet you will practice with the Ideal Gas Law, the Combined Gas Law, as well as the relationships between the number of moles, the mass, and the number of molecules in a gas sample.
omit
Question 1
A mass of nitrogen gas occupies 0.05 m
3
at one atmosphere of pressure (1 atm = 1.01 x 10
5
Pa), and 5 ºC. What will be its new volume if the pressure is increased to 2.5 x 10
5
Pa and the temperature is increased by 2.5 ºC?
1.98 x 10
-2
m
3
1.26 x 10
-1
m
3
3 x 10
-2
m
3
2.02 x 10
-2
m
3
omit
Question 2
How much mass of nitrogen is present in the sample in
Question #1
?
1.2 x 10
-1
kg
2.16 x 10
-3
kg
6.06 x 10
-2
kg
3.03 x 10
-2
kg
omit
Question 3
A sample of 7 grams of oxygen is at STP (1.01 x 10
5
Pa and 0 ºC). How many molecules are present in the sample?
4.21 x 10
24
molecules
6.02 x 10
28
molecules
2.63 x 10
23
molecules
1.32 x 10
23
molecules
omit
Question 4
A certain mass of helium gas occupies 250 cm
3
at 7.5 ºC and 2.5 x 10
5
Pa. How many moles are present in the sample?
0.0268 moles
0.0112 moles
0.0036 moles
1.0023 moles
omit
Question 5
A tiny bubble of air, V = 5 cm
3
, is released by a fish near the bottom of a lake at a depth of 25 meters. If the temperature at the bottom of the lake is 4 ºC and 11 ºC at the surface, what is the volume of the bubble just as it breaks the surface of the lake?
17.7 cm
3
13.0 cm
3
13.8 cm
3
17.3 cm
3
omit
Question 6
Two flasks are connected by an tube that is initially clamped off. One flask, volume of 250 cm
3
, contains argon gas at 0.5 atmospheres while the second flask, volume of 500 cm
3
, contains helium at 1.2 atmospheres. The clamp is removed so that the gases can mix. If the temperature remains constant, what is the final pressure in the double-flask system?
8 x 10
4
Pa
1.67 x 10
4
Pa
7.33 x 10
-1
Pa
9.67 x 10
4
Pa
omit
Question 7
What is the average translational velocity of one nitrogen molecule in the sample in
Question #1
when the gas was at its original temperature, 5 ºC?
1.57 x 10
1
m/sec
4.97 x 10
2
m/sec
1.07 x 10
1
m/sec
3.32 x 10
2
m/sec
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