1. Unit 2: Equilibrium Lesson 4: Predicting Spontaneity

2. Predicting Spontaneity (Examples)
C2H2(g) + 2 Cl2(g) → C2H2Cl4(l) kJ
CH4(g) + O2(g) → CO2(g) + 2 H2O(g) kJ
4 Au(s) + 3 O2(g) kJ → 2 Au2O3(s)
I do – 10 min

3. Brain Break!

4. Le Châtelier’s Principle
Consider the following equilibrium reaction:
CH3CO2H + H2O ⇌ CH3CO2− + H3O+
Think-Pair-Share:
What do you think would happen if CH3CO2H were added to the system?
What if we then added H3O+?
TPS – 10 min

5. Le Châtelier’s Principle
Is this: “If a closed system at equilibrium is subjected to a change, processes will occur that tend to counteract that change.”
In other words, whatever we do, nature tries to undo.

6. Demo of Le Chatelier’s Principle
CoCl H2O ⇌ [Co(H2O)6] Cl-
Predict: What will happen if water is added? What will happen if acetone is added, causing water to be removed?
Observe: What happened?
Explain: Whatever we do, nature tries to undo!
– 15 min

7. Homework:
Pg. 48 #15 (part iii) and 16
5 min