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A simpler, colourful demonstration of an equilibrium that can be switched back and forth by the addition of acid or alkali is that involving dichromate/chromate ions. http://www.practicalchemistry.org/experiments/ intermediate/reversible-reactions/an-equilibrium-involvingchromatevi-and-dichromatevi-ions,284,EX.html The effect of changing conditions on the position of equilibrium should be discussed in terms of these examples and a clear summary that can be applied generally given to the students.
Common misunderstandings and misconceptions This develops into a conceptually difficult area so the use of appropriate analogies is important. It is also useful to use the examples quoted to generate some simple rules that students can apply to the reactions they will be presented with in the examination.
Homework ideas ◆ ◆ ◆
Worksheet 7.3 Reversible reactions and Worksheet 7.8 Heating copper(ii) sulfate crystals Exercise 7.8 Reversible reactions involving inter-halogen compounds Coursebook questions 7.22 to 7.27 and End-of-chapter questions 2 and 6
Original material © Cambridge University Press 2014 © Cambridge University Press 2014 IGCSE Chemistry
Teaching ideas: Chapter 7
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