Using Energy Transfers LO: Describe a use for the energy transferred in a reaction (D) Explain how the energy changes in a reaction can be used (C) Make a conclusion based on you knowledge of reversible reactions(B) Evaluate the usefulness of using energy processes from chemical reactions (A/A*) Starter With whiteboards... What is the symbol for a reversible reaction? What does exothermic mean? What happens to temperature in an endothermic reaction?

Hydrated copper sulphate copper sulphate + water ENDO EXO N H 2 2 NH 3 EXO ENDO

Self heating can How does this work ? Think about how this could be self heating. Think about what was done to make it heat up. What was going on ? Hint – this might have something to do with previous work.

Calcium Oxide Mixes with water Exothermic reaction

Around the Room In Groups. Around the room is some information about the uses of exo and endothermic reactions. One person finds the information and reads it. Remember what you can. Report back to the group. Tell them what the information is. If you forget go back and remember a bit more. Someone else in the group finds the next one. Put the information in order.

Hand warmers Hand warmers are using the recrystallisation of a solid to produce an exothermic release of energy. How can we reverse this to make it so that the hand warmer can be used again ? Sodium ethanoate solution Sodium ethanoate solid EXO

Create a mark scheme

Design A container for self heating food that could be used by mountaineers, or the armed forces.

Advantages and Disadvantages What’s good and bad about using chemical reaction energy changes ?

Definitions Exothermic = heat given out in a reaction. (gets hotter) Endothermic = heat taken in during a reaction. (gets colder or needs a bunsen)