Dynamic equilibrium, position of equilibrium and industry
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The teaching part (1 min) is free to watch. A free account opens the whole lecture: 1 worked example, 5 practice questions, 2 real past-paper questions with the answers explained, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
What this lecture covers
- Reactions that go both ways
- Reversible reactions
- Dynamic equilibrium
Read the transcript of the teaching part
Last time
Before we start: last time, in Energy changes and bond energies, you learned these points. Here they are again on one card. Keep them in mind, because today builds on them.
Reactions that go both ways
Heat blue copper sulfate crystals and they turn white, giving off water. Add the water back and they turn blue again. The reaction goes both ways. In a closed container, a reversible reaction never finishes. It settles into a balance called a dynamic equilibrium, and the factories that make fertiliser and sulfuric acid depend on it.
Reversible reactions
A reversible reaction can go in both directions. We show it with a double arrow. The forward reaction turns reactants into products. The reverse reaction turns products back into reactants. If the forward reaction is exothermic, the reverse reaction is endothermic by the same amount.
Dynamic equilibrium
In a closed container, the forward and reverse reactions happen at the same rate. So the concentrations of all the substances stay constant. Nothing seems to change. But both reactions are still going on, which is why it is called dynamic. It is not that they have stopped. The system must be closed, so that nothing can escape.
How often it comes up
How often Cambridge has asked each part, counted by ExamYard from every past paper in its question bank: Haber and Contact processes · Position of equilibrium · Haber and Contact processes · Reversible reactions and equilibrium.
The whole chapter: Chemical Reactions, Chemical Reactions.
Chapter 6: Chemical reactions
- Collision theory and rate graphs 6 min
- Dynamic equilibrium, position of equilibrium and industry 6 min
- Oxidation numbers and redox 6 min
- Oxidising and reducing agents 6 min
Also for IGCSE Chemistry 0620
Which topics come up most in IGCSE Chemistry 0620 past papers, counted from every paper since 2004.