Thermal energy is transferred through the hydrosphere from warmer latitudes to cooler polar regions largely due to global winds.

The specific heat capacity is the amount of heat energy needed to raise the temperature of one gram of a substance by one degree celcius.

0.897 Jcg C

4.19 Jcg C

0.385 Jcg C

0.840 Jc

g C

The specific heat capacity of water is

extremely large when compare to most other

substances! Sweet.

A simple foam cup calorimeter.

Q mc t

This is the amount of thermal energy that is released or absorbed by one gram of a substance when its temperature changes by one degree celcius.

Q = thermal energy ( J )

m = mass ( g )

c = specific heat capacity ( J/g ºC )

Δt = change in temperature ( ºC )

1) A 350-g mass of water at 12.0ºC is allowed to warm up to 30.0ºC. Determine the amount of thermal energy, Q, absorbed. The theoretical specific heat capacity of water is 4.19 J/gºC.

2.64 x 104 J

2) Determine the quantity of energy required to warm a 2.00-kg block of ice from -25.0ºC to -10.0ºC. The theoretical specific heat capacity of ice is 2.00 J/gºC. Express your answer in kilojoules.

60.0 kJ

4) When 680 J of thermal energy is added to 30.0 g of iron, the temperature of the iron increases by 51.1ºC. What is the experimental specific heat capacity of iron?

0.444 J/gºC

3) Calculate the change in temperature, Δt, that occurs when 30.0 kJ of thermal energy is added to 2.00 kg of copper. The theoretical specific heat capacity of copper is 0.385 J/gºC.

39.0ºC

read pages 376 – 380 pages 379 – 380, Practice Problems #’s 1 – 8

1) 1.51 × 104 J

2) 3.23 × 104 J

3) 1.26 × 103 J

4) 3.00 × 104 J

5) 20 ºC

6) water: 0.119ºC iron: 1.11ºC

7) 0.897 J/gºC

8) 0.130 J/gºC

(see text page 382)

During a phase change, the temperature of water remains constant.

(text page 385)

The heat of fusion of a substance is the amount of energy released or absorbed when it changes from a liquid to a solid, or from a solid to a liquid.

fus

QH

n

fusion

solidification

Q = thermal energy ( kJ )

Hfus = heat of fusion ( kJ/mol )

n = number of moles of substance ( mol )

mn

M

mass ( g )

molar mass ( g/mol )

The heat of vaporization of a substance is the amount of energy released or absorbed when it changes from a gas to a liquid, or from a liquid to a gas.

vap

QH

n

vaporization

condensation

Q = thermal energy ( kJ )

Hvap = heat of vaporization ( kJ/mol )

n = number of moles of substance ( mol )

1) When 4.18 kJ of thermal energy is added to 12.5 g of ice at its melting point, the ice changes phase. Given the molar mass of water is 18.02 g/mol, calculate the experimental heat of fusion of ice.

6.03 kJ/mol

2) Calculate how much thermal energy is required to completely vaporize 30.0 g of liquid water, given that water has a molar mass of 18.02 g/mol and the heat of vaporization of water is 40.65 kJ/mol.

67.7 kJ

3) Determine the number of moles of silver at its melting point that can be melted by the addition of 50.0 kJ of energy, given that the heat of fusion of silver is 11.20 kJ/mol.

4.46 mol

read pages 382 – 389 pages 386 – 387, Practice Problems #’s 9 – 15 D2.3 Check and Reflect

page 390 #’s 1 – 2, 4, 6 – 8, 11 – 23

9) 6.01 kJ/mol

10) 19.2 kJ

11) 2.50 mol

12) 0.385 kJ/mol

13) 3.48 kJ/mol

14) 40.7 kJ/mol

15) 1.13 × 103 kJ