1. Thermochemistry and Thermodynamics

2. Energy
Ability to do work or produce heat

3. Energy Kinetic Energy Potential Energy Energy in motion
Due to the composition or position of an object

4. Law of Conservation of Energy
Energy cannot be created or destroyed, only converted from one form to another

5. Let’s talk terminology.
System: part of a system that a chemist chooses to study
Surroundings: the rest of the universe
Ice and water = System
Beaker, air, and everything else= surroundings
A system can interact with its surroundings.

6. Let’s talk terminology.
Energy transfers involve transfers of heat and/or work.
Internal Energy (E): total energy within a system
Thermal energy: energy associated with random molecular motions
Chemical Energy: energy associated with the bonds and intermoleuclar attractions

7. Let’s talk terminology.
Since energy and work are so closely related, we use the same unit to measure both.
Joule (J)
Calorie (cal): 1 cal = J

8. Heat
The energy transferred between a system and its surroundings as a result of temperature difference
Symbol: q

9. Heat
Endothermic
Exothermic
Heat is absorbed
Heat is released

10. Heat Capacity
The amount of heat needed to increase the temperature of n object exactly 1°C
Depends on mass and chemical composition

11. Specific Heat
Amount of heat required to raise the temperature of 1 g of that substance by 1°C
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12. Specific Heat

13. q = cp m ΔTc Calorimetry Problems
q = amount of heat/energy transferred (Joules)
m = mass of the substance (grams)
ΔTc = temperature change of the substance
Tfinal – Tinitial
cp= specific heat of the substance

14. How much heat is needed to raise the temperature of 20
How much heat is needed to raise the temperature of 20.0 grams of liquid water from 5 °C to 20 °C?

15. How much heat is released by 200
How much heat is released by grams of a solid aluminum as it cools from °C to °C?

16. How much heat is absorbed by 5
How much heat is absorbed by 5.00 grams of copper when it is heated from 0.0 °C to °C?

17. EXIT QUIZ
How many joules of heat are released when 50 grams of a solid magnesium is cooled from 70 °C to 60 °C? cp = J/(g °C).