Chapter 17
Part 4
Solid-Vapor Equilibrium
• Sublimation is a process in which
molecules go directly from the solid
into the vapor phase (deposition is
the reverse process).
Sublimation
Iodine and dry ice are substances that commonly undergo sublimation.
Which of these can reach equilibrium?
Deposition
• The formation of frost.
Boiling
• A substance
boils when the
vapor pressure
of the liquid is
equal to the
atmospheric
pressure.
How could I boil this water?
A
A
A
What is temperature of the water?
A
A
A
Why does water boil at 100°C?
Water Vapor Pressure Table
Temperature
(°C)
0.0
5.0
10.0
12.5
15.0
15.5
16.0
16.5
17.0
17.5
18.0
18.5
19.9
Pressure
(mmHg)
4.6
6.5
9.2
10.9
12.8
13.2
13.6
14.1
14.5
15.0
15.5
16.0
16.5
Temperature
(°C)
19.5
20.0
20.5
21.0
21.5
22.0
22.5
23.0
23.5
24.0
24.5
25.0
26.0
Pressure
(mmHg)
17.0
17.5
18.1
18.6
19.2
19.8
20.4
21.1
21.7
22.4
23.1
23.8
25.2
Temperature
(°C)
27.0
28.0
29.0
30.0
35.0
40.0
50.0
60.0
70.0
80.0
90.0
95.0
100.0
Pressure
(mmHg)
26.7
28.3
30.0
31.8
42.2
55.3
92.5
149.4
233.7
355.1
525.8
633.9
760.0
Is there another way to boil the water?
Is there another way to boil the water?
Is there another way to boil the water?
What is the pressure inside the bell
jar if the water is boiling at 20°C?
Water Vapor Pressure Table
Temperature
(°C)
0.0
5.0
10.0
12.5
15.0
15.5
16.0
16.5
17.0
17.5
18.0
18.5
19.9
Pressure
(mmHg)
4.6
6.5
9.2
10.9
12.8
13.2
13.6
14.1
14.5
15.0
15.5
16.0
16.5
Temperature
(°C)
19.5
20.0
20.5
21.0
21.5
22.0
22.5
23.0
23.5
24.0
24.5
25.0
26.0
Pressure
(mmHg)
17.0
17.5
18.1
18.6
19.2
19.8
20.4
21.1
21.7
22.4
23.1
23.8
25.2
Temperature
(°C)
27.0
28.0
29.0
30.0
35.0
40.0
50.0
60.0
70.0
80.0
90.0
95.0
100.0
Pressure
(mmHg)
26.7
28.3
30.0
31.8
42.2
55.3
92.5
149.4
233.7
355.1
525.8
633.9
760.0
We can make water boil at
“any” temperature.
Water Vapor Pressure Table
Temperature
(°C)
0.0
5.0
10.0
12.5
15.0
15.5
16.0
16.5
17.0
17.5
18.0
18.5
19.9
Pressure
(mmHg)
4.6
6.5
9.2
10.9
12.8
13.2
13.6
14.1
14.5
15.0
15.5
16.0
16.5
Temperature
(°C)
19.5
20.0
20.5
21.0
21.5
22.0
22.5
23.0
23.5
24.0
24.5
25.0
26.0
Pressure
(mmHg)
17.0
17.5
18.1
18.6
19.2
19.8
20.4
21.1
21.7
22.4
23.1
23.8
25.2
Temperature
(°C)
27.0
28.0
29.0
30.0
35.0
40.0
50.0
60.0
70.0
80.0
90.0
95.0
100.0
Pressure
(mmHg)
26.7
28.3
30.0
31.8
42.2
55.3
92.5
149.4
233.7
355.1
525.8
633.9
760.0
234
Elevation = 29,035 ft.
What would happen to this water
as it boiled?
It gets colder
How can we continue to boil the
water as it cools?
Water Vapor Pressure Table
Temperature
(°C)
0.0
5.0
10.0
12.5
15.0
15.5
16.0
16.5
17.0
17.5
18.0
18.5
19.9
Pressure
(mmHg)
4.6
6.5
9.2
10.9
12.8
13.2
13.6
14.1
14.5
15.0
15.5
16.0
16.5
Temperature
(°C)
19.5
20.0
20.5
21.0
21.5
22.0
22.5
23.0
23.5
24.0
24.5
25.0
26.0
Pressure
(mmHg)
17.0
17.5
18.1
18.6
19.2
19.8
20.4
21.1
21.7
22.4
23.1
23.8
25.2
Temperature
(°C)
27.0
28.0
29.0
30.0
35.0
40.0
50.0
60.0
70.0
80.0
90.0
95.0
100.0
Pressure
(mmHg)
26.7
28.3
30.0
31.8
42.2
55.3
92.5
149.4
233.7
355.1
525.8
633.9
760.0
And then when the vapor pressure
of water reaches 4.6 mm Hg.
Water Vapor Pressure Table
Temperature
(°C)
0.0
5.0
10.0
12.5
15.0
15.5
16.0
16.5
17.0
17.5
18.0
18.5
19.9
Pressure
(mmHg)
4.6
6.5
9.2
10.9
12.8
13.2
13.6
14.1
14.5
15.0
15.5
16.0
16.5
Temperature
(°C)
19.5
20.0
20.5
21.0
21.5
22.0
22.5
23.0
23.5
24.0
24.5
25.0
26.0
Pressure
(mmHg)
17.0
17.5
18.1
18.6
19.2
19.8
20.4
21.1
21.7
22.4
23.1
23.8
25.2
Temperature
(°C)
27.0
28.0
29.0
30.0
35.0
40.0
50.0
60.0
70.0
80.0
90.0
95.0
100.0
Pressure
(mmHg)
26.7
28.3
30.0
31.8
42.2
55.3
92.5
149.4
233.7
355.1
525.8
633.9
760.0
What is the boiling point of ethanol at normal air pressure?
What is the boiling point of water at an air pressure of 400 torr?
At what air pressure will Diethyl ether boil at 20°C?
How do these substances compare in terms of Van der Waals forces,
rate of evaporation, vapor pressure, and volatility ?
How do these substances
compare in terms of Van der
Waals forces, rate of
evaporation, vapor pressure,
and volatility ?
“Which would you expect to have
the higher boiling point?
“Which would you expect to have
the higher boiling point?
He = -269˚C
Rn = -62˚C
Homework
 Worksheet 2 Chapter 17
Illustrate the relationship
between ∆H and exo/endo
reactions.
↑Temp shifts reactions in the
endothermic direction