Why do chemical reactions happen? | 16-18 years

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.