Using Energy TransfersLO:

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

N2 + 3 H2 2 NH3

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 OxideMixes with waterExothermic 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 warmersHand 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

DesignA 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 ?

DefinitionsExothermic = heat given out in a reaction. (gets hotter)

Endothermic = heat taken in during a reaction.

(gets colder or needs a bunsen)