Properties of gases and gas laws

1. GAS LAWS
SCIENCE 10

2. The relationship among
the pressure, volume, and
temperature of a gas have
been established through
scientific experiments and
described by the gas laws.
These laws are explained by
the kinetic molecular theory.

3. GAS LAWS
BOYLE’S LAW:
PRESSURE-VOLUME
RELATIONSHIP

4. ROBERT BOYLE
BRITISH SCIENTIST
 He established the P-V
relationship of a gas from his
investigations using air.
 He concluded that for a fixed
amount of gas and at constant T,
the P exerted by the gas is
inversely proportional to the V it
occupies.

5. P ∝
Where ∝ is the proportionality
symbol. Introducing the
proportionality constant k, the
equation becomes
1
V
(at constant pressure) 1
V
P = k or PV=k

6. P ∝
If the pressure is increased, the
volume must decrease to
maintain the constant product,
and vice versa. (Boyle’s law)
1
V
(at constant pressure)
P V

7. P ∝
For a sample of gas under two
different conditions, the following
equation applies:
P1V1=P2V2
where:
P1 = initial pressure V1 = initial volume
P2 = final pressure V2 = final volume
1
V
(at constant pressure)

8. EXAMPLE:
A.
In a 35.0 L automobile airbag, a certain
amount of nitrogen gas exerts a pressure of 745
mm Hg. If the gas is transferred to a 25.0 L bag at
the same temperature, what will be its final
pressure?
Given:
Find:
Solution:

9. EXAMPLE:
A.
Given:V1 = 35.0 L
V2 = 25.0 L
P1 = 745 mm Hg
Find: P2
Solution: P2 =
P2 = 1043 mm Hg
P1V1
V2
= (745 mm Hg)(35.0 L)
25.0 L

10. EXERCISES:
1.
A sample of oxygen has a volume of 10.0 L at
740 torr. What will be its volume if the pressure
becomes 600 torr at the same temperature?
Given:
Find:
Solution:

11. EXERCISES:
2.
The pressure of a 1066 mL gas is 457 mm
Hg. What will be its pressure if the volume is
increased to 750 mL at constant temperature?
Given:
Find:
Solution:

12. GAS LAWS
CHARLE’S LAW:
VOLUME-TEMPERATURE
RELATIONSHIP

13. JACQUES
CHARLES
FRENCH SCIENTIST
 He established that a
constant pressure, the V
occupied by a fixed amount of
gas is directly proportional to
its temperature.

14. V ∝ T
Using the proportionality constant
k, this relationship becomes
Note: T is expressed in kelvin (K)
(at constant pressure)
V = kT

15. V ∝ T
Thus, for a given quantity of gas
at constant pressure, the volume
increases if the temperature
increases, and vice versa, to
maintain the constant ratio.
(Charle’s Law)
(at constant pressure)
V T

16. V ∝ T
For a sample of a gas under two
different conditions:
or V1T2 = V2T1
where:
V1 = initial volume T1 = initial temperature
V2 = final volume T2 = final temperature
(at constant pressure)
V1 = V2
T1 T2

17. EXAMPLE:
A.
A gas-tight syringe contains 25.0 mL of carbon
dioxide at 20.0⁰C. What will be the volume of the
gas if the syringe is dipped in warm water at
37.0⁰C? Note that temperature must be expressed
in kelvin.
Given:
Find:
Solution:

18. EXAMPLE:
A.
Given:V1 = 25.0 L
T1 = 20.0⁰C+273.15 = 293.15 K
T2 = 37.0⁰C+273.15 = 310.15 K
Find: V2
Solution: V2 =
V2 = 26.4 mL
V1T2
T1
= (25.0 mL)(310.15 K)
293.15 K

19. EXERCISES:
1.
A sample of carbon monoxide is stored in a 3.20
L container at 125⁰C. Calculate the temperature at
which the gas will occupy 1.54 L if the pressure is
held constant.
Given:
Find:
Solution:

20. EXERCISES:
2.
On hot days, you may notice that sealed potato
chip bags seem to inflate. If you have a 245 mL
potato chip bag at 292 K and you place it inside the
trunk of a car with a temperature of 333 K, what will
be the new volume of the bag if the surrounding
pressure remains the same?
Given:
Find:
Solution: