Why do chemical reactions happen? | 16-18 years

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Introduce students to entropy and explore why chemical reactions happen using role play, discussion and demonstrations in this lesson plan for 16–18 year olds.

In this activity, entropy is introduced to students in a qualitative way, as a means of explaining why chemical reactions happen. Students will explore how:

Disorder increases when spontaneous chemical reactions occur.
An increase in disorder can be represented by wider distribution of energy or particles.
Thermodynamics is responsible for determining whether chemical reactions ‘go’ or not and that reactions themselves are not ‘alive’, so cannot ‘decide’.

The question ‘Why do chemical reactions happen?’ is a basic one to answer. The best time to approach this issue is within a series of lessons on thermodynamics, once students are used to calculating enthalpy change values.

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