1. Properties of Water
The first image taken by humans of the whole Earth. Photographed by the crew of Apollo 8, the photo shows the Earth at a distance of about 30,000 km. Space has no respect for “North” and “South” as the southern most tip of South America is at the top of the photo.

2. Boiling Point and Freezing Point
Substance
Formula Mass, g
Melting Point, C
Boiling Point, C
Water, H2O
18.02
100
Ammonia, NH3
17.04
-77.7
-33.35
Methane, CH4
16.05
-182.5
Methanol, CH3OH
32.04
-97.8
64.96
Ethanol, C2H5OH
46.08
-117.3
78.5
Sulfur dioxide, SO2
64.07
-72.7
-10
Carbon dioxide, CO2
44.01
-56.6
@5.2 atm
-78.5
sublimes
Source: CRC Handbook of Chemistry and Physics

3. Boiling Points for Water at Altitude
Altitude, ft
Boiling point of water, °C
0' (0m)
100°C
500' (152.4m)
99.5°C
1,000' (304.8m)
99°C
2,000' (609.6m)
98°C
5,000' (1524m)
95°C
6,000' (1828.8m)
94°C
8,000' (2438.4m)
91.9°C
10,000' (3048m)
89.8°C
12,000' (3657.6m)
87.6°C
14,000' (4267.2m)
85.5°C
Source: NOAA

4. Density
Water reaches a maximum density of 1.00 g/cm3 at a temperature of 3.98C.
Water expands (becomes less dense) as it freezes

5. Rock Weathering
The expansion of freezing water exerts sufficient force to fracture rock, and is a significant cause of rock weathering.

6. Water’s Thermochemistry
Specific heat and Latent heat of phase change, as they apply to water.

7. Units for Measuring Heat
The Joule is the SI system unit for measuring heat:
The calorie is the heat required to raise the temperature of 1 gram of water by 1 Celsius degree
The British thermal unit (BTU or Btu) is the amount of energy needed to heat one pound of water by one degree Fahrenheit.

8. Specific Heat
The amount of heat required to raise the temperature of one gram of substance by one degree Celsius.

9. Specific Heat
The amount of heat required to raise the temperature of one gram of substance by one degree Celsius.
Substance
Specific Heat (J/g·K)
Water (liquid)
4.18
Ethanol (liquid)
2.44
Water (solid)
2.06
Water (vapor)
1.87
Aluminum (solid)
0.897
Carbon (graphite,solid)
0.709
Iron (solid)
0.449
Copper (solid)
0.385
Mercury (liquid)
0.140
Lead (solid)
0.129
Gold (solid)

10. Specific Heat and Climate
Santa
Barbara CA
How does water contribute to the moderation of climate in coastal communities?

11. Climate Comparison Visalia, CA Jan Feb Mar Apr May Jun
Average high in °F: 55 61 67 73 82 89
Average low in °F: 39 42 46 49 56 62
Av. precipitation in inch:
1.93
1.85
2.01
0.94
0.35
0.16
Santa Barbara, CA
Jan
Feb
Mar
Apr
May
Jun
Average high in °F: 65 66 69 70 71
Average low in °F: 46 48 50 52 55 58
Av. precipitation in inch:
4.37
4.57
2.91
1.22
0.31
0.08
Source: USClimateData.com

12. Climate Comparison Visalia, CA Jul Aug Sep Oct Nov Dec
Average high in °F: 94 93 88 78 64 55
Average low in °F: 67 65 60 53 44 38
Av. precipitation in inch:
0.16
0.59
1.22
1.73
 Santa Barbara, CA
Jul
Aug
Sep
Oct
Nov
Dec
Average high in °F: 75 76 73 69 65
Average low in °F: 60 56 50 47
Av. precipitation in inch:
0.04
0.16
0.91
1.77
3.03
Source: USClimateData.com

13. Calculations Involving Specific HeatOR
cp = Specific Heat
Q = Heat lost or gained
T = Temperature change
m = Mass

14. Energy and Phase Change
Along LEG ‘A’ water exists as a solid (ice), and the temperature increases as energy is absorbed.
The energy required to change the temperature of the ice is the specific heat of ice

15. Energy and Phase Change
At 0 C a phase change begins:
Moving from left to right along LEG ‘B’, ice is melting to form liquid water
Moving from right to left along LEG ‘B’, liquid water is freezing to form ice
The distance of LEG ‘B’ along the Energy axis (x-axis) is known as the Heat of Fusion
Note that temperature remains constant during a phase change!

16. Heat of Fusion
The energy that must be absorbed in order to convert solid to liquid at its melting point
The energy that must be removed in order to convert liquid to solid at its freezing point.
The heat of fusion of water is 334 Joules/gram

17. Energy and Phase Change
Once ice has completely melted, the temperature begins to increase again (LEG ‘C’), as the energy absorbed by water is no longer going toward changing the phase of the substance.
The energy required to change the temperature of the liquid water is its specific heat

18. Energy and Phase Change
At 100 C, a second phase change begins:
Moving from left to right along LEG ‘D’, water is boiling to form water vapor
Moving from right to left along LEG ‘D’, water vapor is undergoing condensation to form liquid water
The distance of LEG ‘D’ along the Energy axis (x-axis) is known as the Heat of Vaporization
Note that temperature remains constant during a phase change!

19. Heat of Vaporization
The energy that must be absorbed in order to convert a liquid to gas at its boiling point.
The energy that must be removed in order to convert a gas to liquid at its condensation point.
The heat of vaporization of water is 2260 Joules/gram

20. Energy and Phase Change
Once all of the liquid water has vaporized, the temperature begins to increase again (LEG ‘E’), as the energy absorbed by water is no longer going toward changing the phase of the substance.
The energy required to change the temperature of the steam is its specific heat

21. Latent Heat – Sample Problem
Problem: The heat of fusion of water is 334 J/g.
How much energy is needed to convert
60 grams of ice at 0C to liquid water at 0C?
Mass
of ice
Heat of
fusion

22. Latent Heat – Sample Problem
Problem: The molar heat of fusion of water is
6.009 kJ/mol. How much energy is needed to convert
60 grams of ice at 0C to liquid water at 0C?
Mass
of ice
Molar
Mass of
water
Heat of
fusion