1. Enthalpy, Entropy, and Gibb’s Free Energy
Accompanies the Lab on p574
Enthalpy, Entropy, and Gibb’s Free Energy

2. Calculating the “change” in….
= CHANGE = Final – Initial ie….. The change in temperature when water is heated from 28 degrees Celsius to 104 degrees Celsius is…. T = 104 – 28 = 76 degrees Celsius

3. Change in Enthalpy ( H) Measure of energy in a system
Melting = (-)
Freezing =
Bomb =
Endothermic = positive H
Exothermic = negative H
100
ice 50
(+)
liquid
(-) 20
Time

4. Change in Entropy ( S) Measure of randomness in a system
S = lots – little = (+)
Melting = (+)
Freezing =
Bomb =
(-)
(+)
Organized-
little randomness
Unorganized-
lots randomness

5. Gibbs Free Energy ( G) Temperature Dependent (T) G = H – T S
Measures if a reaction will happen on its own (spontaneous) or if it will need help (fire, catalyst, etc…)
G = (-) = spontaneous , ex: melting
G = (+) = nonspontaneous, ex: freezing

6. Homework:
READ p
Questions
p555 #6
P559 #11-13, 15