1. LECTURE 8.3 – HEATING CURVES

2. Today’s Learning Targets
7.3 – I can draw a phase diagram to describe how pressure and temperature are related and discuss what a triple point is.
7.4 – I can analyze and draw a heating curve to describe how energy is lost or gained while a substance changes phases. I can identify on the graph the Hfusion and the Hvaporization.
7.5 – I can describe a reaction using the ideas of enthalpy and entropy.

3. Today’s Focus Question
How much energy is required to turn my Flamin’ Hot Cheetos into a liquid?

4. What are enthalpy and entropy?

5. I. Enthalpy (ΔH)
Enthalpy is a measure of the total energy that a system has.
Amount of energy released or absorbed during a process/reaction.
Measured in kilojoules (kJ)

6. II. Entropy (ΔS) The universe tends towards disorder.
Entropy is the measurement of the randomness or disorder of a system.
More energy = more disorder
Measure in J/K

8. How are enthalpy and phase changes related?

9. I. ΔHfusion and ΔHvaporization
Large amount of energy that is required to change phases
ΔHfusion = Energy to change solid to a liquid.
ΔHvaporization = Energy to change liquid to a gas.
ΔHfreezing = Energy to change liquid to a solid
ΔHcondensation = Energy to change gas to a liquid

10. II. Heating Curves
Heating curves are graphs of the relationship between temperature and time.
Allow us to identify important values

11. ΔH of vaporization/condensation
ΔH of fusion/freezing