International Baccalaureate 2016 Syllabus

1. Equilibrium
J Midgley
Head of Chemistry
Guernsey Grammar and Sixth Form Centre
2015
these slides are in no way endorsed by
the ………………………………..

2. Essential Understandings
Many reactions are reversible. These reactions will reach a state of
equilibrium when the rates of the forward and reverse reaction are
equal. The position of equilibrium can be controlled by changing the
conditions.
A state of equilibrium is reached in a closed system when the rates of
the forward and reverse reactions are equal.

3. Visualisation

4. Resources
Experiments
Videos
Tutorials
Old syllabus Questions and Answers
Beyond the syllabus

5. Criteria for establishing equilibirum
1. Rate of forward = rate of backward reaction
2. Closed system…..
3. Equilibrium is the state of equal,
opposite rates, not equal concentrations.

6. 7.1 Kc from the chemical equation
1. In LHS finish the expression for Kc.
2. Write the rules for working out Kc.
3. Write out the original reaction from the Kc
expression above.

7. Problems - write Kc expression for...
(The IB will only ask for homogeneous
equilibria - catalyst need not be in same phase)
1. CH3COOH(l)+CH3CH2OH(l)⇌CH3COOCH2CH3(l)+H2O
2. 2SO2(g)+O2(g)⇌2SO3(g)
3. N2(g)+3N2(g)⇌2NH3(g)

8. 7.2 Magnitude of Kc
The Haber Process ……
Review effects of changing T,P on position of
equilibirum and hence value of Kc.

9. The Contact Process
Questions on Contact Process Answers.
Fabulous schematic and questions to test your
understanding.

10. Kc and Q
When Kc = Q we have equilibirum.
If Q > Kc then equilibirum shifts to _____.
If Q < Kc then equilibirum shifts to _____.

11. Q vs Kc

12. Le Chatelier’s Principle
Animation here.

13. Homework
Create a thoughtful colourful infosplurge
contrasting the Haber process and the Contact
process.