1. CHEMISTRY 161
Chapter 5

2. Classification of Matter
solid liquid gas

3. 1. Gases
substances that exist in the gaseous phase under normal atmospheric conditions
T = 25oC p = 1 atm

4. HF, HCl, HBr, HI
CO, CO2
CH4, NH3, H2S, PH3
NO, NO2, N2O
SO2

5. Jupiter
(H2, He) Io
(SO2)

6. Helix Nebula
Orion Nebula

7. Hindenburg (1937)

8. molecules/atoms of gas are constantly in motion
2. Pressure Ar
molecules/atoms of gas are constantly in motion

9. Atmospheric Pressure

10. Standard Atmospheric Pressure
760 mm at 273 K at sea level
Torricelli
barometer
1 atm = 760 mm Hg = 760 torr
pressure of the atmosphere is balanced by pressure exerted by mercury

11. SI units
force
pressure =
area
p = F / A
[p] = Nm-2 = kg m-1 s-2 = Pa

12. pressure measurement
manometer

13. 3. Gas Laws 3.1. pressure p versus volume V
3.2. temperature T versus volume V
3.3. volume V versus amount n
p, V, T, n

14. (temperature is constant)
3.1. Boyle’s Law
pressure – volume
relationship
(temperature is constant)
Boyle
( )

15. p ∞ 1/V

16. p ∞ 1/V p = const/V p × V = const p1 × V1 = const p2 × V2 = const
p1 × V1 = p2 × V2

17. (pressure is constant)
3.2. Gay-Lussac’s Law
temperature – volume
relationship
(pressure is constant)
Gay-Lussac
( )

18. V ∞ T

19. V ∞ T V = const’ ×T V/T = const’ V1 / T1 = const’ V2 / T2 = const
V1 / T1 = V2 / T2

20. (pressure and temperature
3.3. Avogadro’s Law
amount – volume
relationship
(pressure and temperature
are constant)
Avogadro
( )

21. 2 H2(g) + O2(g) → 2 H2O(l)
n ∞ V

22. n ∞ V n = const’’ × V n/V = const’’ n1 / V1 = const’’
n1 / V1 = n2 / V2

23. SUMMARY p ∞ 1/V V ∞ T n ∞ V 3.1. Boyle’s Law 3.2. Gay-Lussac’s Law
3.3. Avogadro’s Law
p ∞ 1/V
V ∞ T
n ∞ V

24. Homework
Chapter 5, p
problems