1. Heat in Changes of State

2. GLE
Heats of Fusion, Solidification, Vaporization, and Condensation
Understanding a graph showing the heating curve of water
Objective
Student will classify, by type, the heat changes that occur during melting, freezing, boiling, and condensing.

3. Melting Ice
An ice cube placed on a table in a warm room is the system and the table and air around it are the surroundings.
The temperature of the ice remains at 0oC until all the ice has melted.
The temperature of the water begins to increase only after all the ice has melted.
Where have we discussed something similar?

4. Heats of Fusion and Solidification
Molar Heat of Fusion
Heat absorbed by one mole of a substance in melting from a solid to a liquid at a constant temperature
∆ H fus
Molar Heat of Solidification
Heat lost when one mole of a liquid solidifies at a constant temperature
∆ H solid

5. Heat of Fusion of Ice

6. Heat of Fusion Mini-Lab
For the activity
Hypothesis
Experimental Plan/Experiment
Data
Analysis and Conclusions
Conclusion Regarding Hypothesis
Supported
Not Supported
Contradicted
Give a connection for the activity with the real world

7. Heat of Fusion Mini-Lab
For the activity
Hypothesis – Ice melting results in measurable heat of fusion
Experimental Plan/Experiment - Handout
Data – (Model Mini-Lab)
Analysis and Conclusions – Mini-Lab questions
Conclusion Regarding Hypothesis
Supported
- Real world connection – re-useable cold pack.

8. Heat of Fusion Mini-Lab
Calculations
∆ H
= mH2O (g) x CH2O (J/g oC) X ∆T (oC)
mH2O = 70 g (1 g = 1 mL)
CH2O = 4.18 J/g oC
∆T = T (Warm Water) – T (Just After Ice Melts)
∆ H Fus
= ∆ H / moles ice melted
Moles ice melted = Mass Ice (g) x (1 mole H2O/18 g H2O)

9. Heats of Vaporization and Condensation
Molar Heat of Vaporization
Heat necessary to vaporize one mole of a give liquid
∆ H vap
Molar Heat of Condensation
Heat released when one mole of vapor condenses
∆ H cond

10. Heating Curve for Water

11. Heat of Solution Molar Heat of Solution Example ∆ H soln
Heat changed caused by dissolution of one mole of a substance
∆ H soln
Example
CaCl2 (s) H2O (l) Ca 2+ (aq) + 2 Cl- (aq)
∆ H soln = kJ/mol
Where did we see this used before?

12. Practical Application

13. Homework In Chapter 11 of Chemistry Text Sample problem 11-5 p. 311
Read the problem
Work practice problem #22
Sample problem 11-6 p. 313
Work practice problem #24
Page 323
Problems # 64, 70, and 73