- Boyle's law states that the volume of a gas is inversely proportional to its pressure when temperature is kept constant. It describes the relationship between the pressure and volume of a gas. - Charles' law describes how the volume of a gas changes with temperature. It states that the volume of a gas increases or decreases proportionally with an increase or decrease in its temperature. - The combined gas law combines Boyle's and Charles' laws and describes the relationship between pressure, volume, and temperature for a gas.

1. THE GAS
LAWS

2. BOYLE’S LAW
The inverse relationship
between pressure and volume
It states that the volume of a
sample of gas changes
inversely with the pressure of
the gas as long as the
temperature and the amount of
the gas remain constant.

3. When the pressure of the gas
decreases, the volume of the
gas increases.
When the pressure of a gas
increases, the volume of the gas
decreases.
P1V1 = P2V2

4. SAMPLE PROBLEMS:
1. A tank of nitrogen has a
volume of 14.0 L and a
pressure of 760.0 mmHg. Find
the volume of the nitrogen
when its pressure is changed to
400.0 mmHg while the
temperature is held constant.

5. 2. A 200-L helium gas at a
pressure of 280
C and a
pressure of 2.0 atm was
transferred to a tank with a
volume of 68.0 L. What is the
internal pressure of the tank
if the temperature is
maintained?

6. 3. A balloon contains 14.0 L of
air at a pressure of 760 torr.
What will the volume of the air
be when the balloon is taken to
a depth of 10 ft in a swimming
pool, where the pressure is 981
torr? The temperature of the air
does not change.

7. CHARLES’ LAW
States that the Kelvin temperature and
the volume of a gas are directly related
when there is no change in pressure or
amount of gas.
The relationship between volume and
temperature was first observed by
French physicist and balloonist Jacques
Charles.

8. 2
2
1
1
T
V
T
V
=
2
2
1
1
T
V
T
V
=

9. SAMPLE PROBLEMS
1. A balloon has a volume of
2500.0 mL on a day when
the temperature is 30.00
C. If
the temperature at night falls
to 10.00
C, what will the
volume of the balloon if the
pressure remains constant?

10. 2. Find the final
temperature of a 2.00- L
gas sample at 20.00
C
cooled until it occupies a
volume of 500 mL.

11. Do the ff. exercises:
1. A sample of freon gas used in
air conditioner has a volume of
325.0 L and a pressure of 96.3
kPa at 200
C. What will the
pressure of the gas be when its
volume is 975.0 L at 200
C?

12. 2. A balloon contains 30.0L
of helium gas at 100 kPa.
What is the volume when
the balloon rises to an
altitude where the pressure
is only 25.0 kPa?

13. 3. What is the volume of a
sample of thane at 467K
and 2.25 atm if it occupies
1.405 L at 300K and 2.25
atm?

14. 4. The gas in a 1.00-L bottle
at 250
C can be put into a
0.946 bottle at the same
pressure if the temperature
is reduced. What
temperature is required?

15. THE COMBINED GAS LAW
The two gas laws can be
combined and treated as a
single law which describes the
relationship among the
pressure, volume and
temperature of a constant
amount of gas.

16. SAMPLE PROBLEMS:
1. A given mass of gas has a
volume of 800.0 mL at –23.00
C
and 300.0 torr. What would the
volume of the gas be at 27.00
C
and 600.0 torr of pressure? The
amount of gas is constant.

17. 2. A 5.0 –L air sample at a
temperature of –50.00
C has
a pressure of 107.0 kPa.
What will the new pressure
be if the temperature is
raised to 100.00
C and the
volume expands to 7.0 L?

18. 3. A 3.50-L gas sample at 200
C
200
C and a pressure of 86.7 kPa
is allowed to expand to a
volume of 8.0 L. The final
pressure of the gas is 56.7 kPa.
What is the final temperature of
the gas?

19. 5. A weather balloon is filled with
16.0 L of helium at a
temperature of 260
C and a
pressure of 700 mm hg. What is
the pressure of the helium in
the balloon in the upper
atmosphere when the
temperature is -330
C and the
volume becomes 35.oL

20. THE IDEAL GAS LAW
The law that describes the
pressure, volume,
temperature, and number
of moles of a gas.

21. PV= nRT
Where:
P= pressure of the gas
V= volume of the gas
n= amount of gas
R= ideal gas constant
T= temperature of the gas

22. At STP,
P= 1.0 atm= 101.325 kPa
V= 22.4 L
n= 1.0 mole
T= 273 K
R= 0.0821 atm x L/ mol x K
= 8.31kPa x L/ mol x K

23. SAMPLE PROBLEMS:
1. What volume will
1.27 mol of helium
gas occupy at STP?

24. 2. How many moles of
gas are contained in a
50.0-L cylinder at a
pressure of 100.0 atm
and a temperature of
35.00
C?

25. 3. What pressure will be
exerted by 0.450 mol of a
gas at 250
C if it is
contained in a vessel
whose volume is 0.65 L?

26. 4. You fill a rigid steel
cylinder with a volume of
20.0 L with nitrogen gas to
a final pressure of 20 000
kPa at 270
C. How many
moles of nitrogen gas does
the cylinder contain?

27. Answer the following
exercises:
1. A deep underground cavern
contains 2.24 x 106
L of
methane gas(CH4) at a pressure
of 1,500 kPa and a temperature
420
C. How many kg of methane
does this gas deposit contain?

28. 2. The volume of a gas-
filled balloon is 30.0 L at
40.00
C and 150 kPa
pressure. What volume
will the balloon have at
STP?

29. 3. The volume of a sample
of CO is 405 mL at 10.0
atm and 467 K. What
volume will it occupy at
4.29 atm and 467 K?

30. 4. When a rigid hollow
sphere containing 680 L of
helium gas is heated from
300 K to 600 K, the
pressure of the gas
increases to 1 800 kPa.
How many moles of
helium are in the sphere?

31. 5. A container with an initial
volume of 1.0 L is occupied by a
gas at a pressure of 150 kPa at
250
C. By changing the volume,
the pressure of the gas
increases to 600 kPa as the
temperature is raised to 1000
C.
What is the new volume?

32. GAY- LUSSAC’S LAW
Temperature and
pressure relationship
The pressure of a gas
is directly related to its
Kelvin temperature.

33. This means that an increase in
temperature increases the
pressure of a gas, and a
decrease in temperature
decreases the pressure of the
gas as long as the volume and
number of moles of the gas
remain constant.

34. 2
2
1
1
V
n
V
n
=
2
2
1
1
T
P
T
P
=

35. SAMPLE PROBLEMS:
1. The gas left in a used
aerosol can is at a
pressure of 100 kPa at
270
C. If the can is thrown
onto a fire, what will the
internal pressure be
when its temperature
reaches 9270
C?

36. 2. The pressure in automobile
tire is 200 kPa at a
temperature of 270
C. At the
end of a journey on a hot
sunny day, the pressure has
risen to 223 kPa. What is
the temperature of the air
in the tire?

37. AVOGADRO’S LAW
Equal volumes of
gases at the same
temperature and
pressure contain
equal numbers of
particles.

38. 2
2
1
1
n
V
n
V
=

39. SAMPLE PROBLEMS
If 23.1 g of oxygen
occupies a volume of
5.0 L at a particular
pressure and
temperature, what
volume will 2.5 g of
oxygen gas occupy
under the same
conditions?

40. Determine the volume
in liters occupied by
0.202 mol of a gas at
STP.
How many oxygen
molecules are in 3.3
liters of oxygen gas at
STP?

41. Determine the volume
in liters occupied by
14.0 g of N2 at STP.
What volume is
occupied by 4.02 x
1022
molecules of H2
at STP?

42. DALTON’S LAW
At constant volume and
temperature, the total
pressure exerted by a
mixture of gases is equal
to the sum of the partial
pressures of the
component gases.

43. Ptotal= P1+P2+P3……

44. SAMPLE PROBLEMS
Determine the total
pressure of a gas
mixture that contains
oxygen, nitrogen, and
helium if the partial
pressures of the gases
are 20.0 kPa, 46.7 kPa,
and 26.7 kPa
respectively.

45. A balloon contains mostly He
and a little methane. The partial
pressure of helium is 101.2 kPa.
If the pressure inside the
balloon is 101.3 kPa, what is the
partial pressure of methane?
A 5.73- L flask at 250
C contains
0.0388 mol of N2, 0.1 47 mol of
CO, and 0.0803 mol of H2. What
is the pressure in the flask in
atm and kPa?