1. 2.3
Thermal Energy
Transfer In
The
Hydrosphere

2. The Unique Properties of Water
High Surface Tension
More than one state
High Melting & Boiling Points
Density
High Specific Heat Capacity
Unique heat of Fusion
Unique heat of Vaporization

3. 1. High Surface Tension
Caused by adhesive and cohesive forces of attraction
Enables insects and other organism to walk on the surface

4. 2. More Than One State solid sublimation melting freezing liquid gas
It can exist in 3 phases …..change occurs when energy is added or taken away
solid
sublimation
melting
freezing
liquid
gas

5. endothermic changes of state:
-melting, evaporation, sublimation (solid to gas)
exothermic changes of state:
-freezing, condensation, sublimation (gas to solid)

6. When water has changed from one state to another a phase change has occurred
Gas
Graph showing phase changes
Liquid
Solid

7. 3. High Melting and Boiling Points
Allows for a wide range of temperatures on earth

8. 4.Density Freezes it forms a solid crystal lattice
Water is most dense at 4ºC (when it is still a liquid)
At O ºC Water:
Freezes
it forms a solid crystal lattice
molecules are farther apart making it less dense …. enabling it to float

9. Water freezes on the surface first (top to bottom)
What would happen to organisms if ice formed at the bottom first?
20 ºC
4 ºC
0 ºC

10. 5. High Specific Heat Capacity
Water absorbs a lot of energy and releases it slowly…. helping to moderate coastal temperatures
Specific Heat: Is the amount of energy to raise 1g of a substance 1ºC ….it is high for water

11. Quantity of Thermal Energy
Is represented as Q
It is the amount of thermal energy absorbed or released when temperature changes

12. to calculate heat energy use the following formula:
Q = mcΔt
where: Q = heat energy in Joules (J)
m = mass in grams (g)
Δt = change in temperature in °C
c = specific heat capacity in J/gC

13. Example 1
Calculate the heat required to raise the temperature of 200 g of ethanol from 20.0°C to 45.0°C.
Q = mcΔt
= (200 g)(2.46 J/gC) (45.0C C)
= J
= 1.23  104 J

14. Example 2
Calculate the heat required to raise the temperature of 400 g of ethanol from 10.0°C to 50.0°C.
Q = mcΔt
= (400 g)(2.46 J/gC) (50.0C C)
= J
= 3.94  104 J

15. 6. Unique Heat of Fusion Hfus = Q n Q = nHfus
Is the amount of energy required to convert 1 gram of solid into a liquid state
Hfus = Q n
Q = nHfus or
where: Hfus = heat of fusion in J/mol or kJ/mol
n = number of moles in mol
Q = heat energy in J or kJ

16. Example 1
Calculate the heat of fusion of sulphuric acid if 2000 J of heat energy is applied to mol.
Hfus = Q/n
= 2000 J/0.694 mol
= … J/mol
= 2.88  103 J/mol

17. Example 2
Calculate the heat of fusion of sulphuric acid if 1050 J of heat energy is applied to mol.
Hfus = Q/n
= 1050 J/0.231 mol
= … J/mol
= 4.55  103 J/mol

18. 7. Unique Heat of Vaporization
Is the amount of energy that is needed to convert 1 gram of a liquid into gas
Hvap = Q n or
Q = nHvap
where: Hvap = heat of vaporization in J/mol or kJ/mol
n = number of moles in mol
Q = heat energy in J or kJ

19. Example 1
Calculate the heat of vaporization of ethanol if J of heat energy is applied to mol.
Hvap = Q/n
= 5000 J/0.325 mol
= …J/mol
= 1.54  104 J/mol

20. Heating Curve For Water Temperature (C) Time (min) phase change
H2O(l)  H2O(g)
H2O(g)
temperature change BP
100C
Temperature
(C)
H2O(l) temperature change
phase change
H2O(s)  H2O(l) MP
0C
H2O(s) temperature change
Time (min)