1. Calculating Gas Volumes and Pressures
1: How do we calculate gas volume and pressure;
2: How is this applied to real life situations ?

2. Pressure Decreases, Volume increases…

3. Why is breathing difficult at great altitudes ?

4. Scattering Ashes into ….Space !

6. Submarine Escape Training

7. Pressure Increases…Volume Decreases:

8. Gas Pressure and Volume Data

9. Air Tanks: air needs to be compressed to provide enough for the necessary dive length.
The gas bottle needs to be able to store a large volume of gas at atmospheric pressure into a few litres. Containing this gas creates a huge pressure.

10. Boyle’s Law a
Volume inversely proportional to pressure. b c

11. 1: Gas Volume : Pressure relationship-

12. V1xP1 = V2xP2 or V1P1 = V2x P2 …. 2 x 4 = 1 x ? 3 x 4 = ? X 6

13. V1P1=V2P2 Relationship
Volume 1 (V1) (m3)
Pressure 1 (P1) (Pa)
Volume 2 (V2) (m3)
Pressure 2 (P2) (Pa) 6 3 9
240 46
6826
26 000
86 420
482
6.3 x 108
2.7 x 105
8 x 10 8

14. V1P1=V2P2 Relationship
Volume 1 (V1) (m3)
Pressure 1 (P1) (Pa)
Volume 2 (V2) (m3)
Pressure 2 (P2) (Pa) 6 3 9 2
240 46
6826
1.68
26 000
1602.1
86 420
482
6.3 x 108
2.7 x 105
212,625
8 x 10 8

15. Applying this relationship:
A cylinder of O2 contains 0.3m3 of gas at a pressure of Pa (1.4 x 107).
If all the O2 is released without changing temperature, what will its volume be ? ( Atmospheric Pressure = Pa)

16. Applying this relationship:
A cylinder of O2 contains 0.3m3 of gas at a pressure of Pa (1.4 x 107).
If all the O2 is released without changing temperature, what will its volume be ? ( Atmospheric Pressure = Pa)
V2 = P1V1 / P2
V2 = 0.3 m3 x Pa / Pa
V2 = 42 m3

17. Exam Question:
V1P1=V2P2
A bicycle pump compresses m3 of air at atmospheric pressure to a volume of m3. What is the pressure of the compressed gas ?
(Atmospheric Pressure = Pa)
P2 =V1xP1 / V2

18. Exam Question:
V1P1=V2P2
A bicycle pump compresses m3 of air at atmospheric pressure to a volume of m3. What is the pressure of the compressed gas ?
(Atmospheric Pressure = Pa
Ie, P2 = V1 x P1 / V2
(V1) m3 x (P1) Pa/ m3
P2 = Pa
P2 =V1xP1 / V2

19. Why doing work on a gas increases its temperature:
As gas particles are compressed, the pressure increases.
The particles hit each other and the moving cylinder more frequently so this speeds up their movement.
Faster moving particles have a higher temperature.

20. 2: Temperature and Gas Pressure:

21. If the temperature of a gas is increased at constant pressure, the volume increases.
A hot air balloon contains m3 of air at 100 0C (373 K). What volume of air at 5 0C (278 K) is needed to fill the balloon ?
Use K for temperature units.
V2 = (V1/T1) x T2

22. Temperature and Volume in Gas (You must convert 0C to 0K before calculation)
Temperature 1 (0C)
Volume 1 (m3)
Temperature 2 (0C)
Volume 2 (m3) 1 12
100 4
200
420
2.4
1360 20
0.1
-40
0.4
124

23. 3: Higher: Combining the equations-
A 0.1 m3 gas cylinder can stand a pressure of 20 x 107 Pa before breaking. It is filled with gas at 2 x107 Pa at 200C. What temperature can it stand before it explodes ?
( Convert 0C to K )
2 X 9
= 6 3

24. 3: Higher: Combining the equations-
A 0.1 m3 gas cylinder can stand a pressure of 20 x 107 Pa before breaking. It is filled with gas at 2 x107 at 200C. What temperature can it stand before it explodes ?
( Convert 0C to K )
Ie, P2 =
(P1) 2 x 107 x (V1) 0.1 m3 / (T1) 293 K =
(P2) 20 x 107 x (V2) )0.1 m3 /
= 2930 K (2657 0C)

25. Try this……
A gas bottle, volume 0.15 m3, is normally stored at 200C at a pressure of 2.3 x 108 Pa. What is the pressure in the bottle if the temperature rises to 400C ?

26. Try this……
A gas bottle, volume 0.15 m3, is normally stored at 200C at a pressure of 2.3 x 108 Pa. What is the pressure in the bottle if the temperature rises to 400C ?
Ie, what is P2 ?
(P1) 2.3 x 108 Pa x (V1) 0.15 m3 / 293 K =
P2 = (T2 x ) / V2
P2 = (313 K x ) / 0.15m3 =
P2 = Pa or 2.45 x 108 Pa
2 x 9
= 6 3

27. Higher Level Progression Question (A)
A gas bottle, volume 0.15 m3, is normally stored at 210C at a pressure of 2.3 x 108 Pa. What is the pressure in the bottle if the temperature rises to 720C ?

28. Extension Questions (H+F)3
Extension Questions (H+F)
1: Patients with lung problems often need to be given extra O2 to breathe. A gas cylinder has a volume of 0.2 m3. It stores O2 at a pressure of Pa. What would the volume of O2 be if it were released at atmospheric pressure (= Pa) ?
2: 1000 m3 of air is used to fill a hot air balloon. The air starts at 100C (283K) and is heated to 700C (343K). What is the volume of air inside the balloon ?