Memory Anchor:

• Super Challenge:

  Stretch:

  Challenge:

Key Questions:

1. What does conservation of energy mean?
   • Energy is conserved in chemical reactions. The amount of Energy in the universe at the end of a chemical reaction is the same as before the reaction
2. In what circumstance is energy transferred to the surroundings during a chemical reaction?
   • If a reaction transfers Energy to the surroundings the product molecules must have less Energy than the reactants, by the amount transferred.
3. What happens to the energy in an exothermic reaction?
   • An exothermic reaction is one that transfers Energy to the surroundings so the temperature of the surroundings increases.
4. What are three examples of exothermic reactions?
   • Exothermic reactions include combustion, many oxidation reactions and neutralisation.
5. What is an example of an exothermic reaction in everyday life?
   • Everyday uses of exothermic reactions include self-heating cans and hand warmers.
6. What happens to the energy in an endothermic reaction?
   • An endothermic reaction is one that takes in Energy from the surroundings so the temperature of the surroundings decreases.
7. What are three examples of endothermic reactions?
   • Endothermic reactions include thermal decompositions and the reaction of citric acid and sodium hydrogencarbonate
8. What is an example of an endothermic reaction in everyday life?
   • Everyday uses of endothermic reactions are some sports injury (ice) packs.
9. When a chemical reaction occurs and the temperature of the surroundings has increased, is it an exothermic or endothermic reaction?
   • When a chemical reaction occurs and the temperature of the surroundings has increased the chemical reaction is exothermic.
10. What are the advantages of using exothermic reactions for hand warmers?
    • The advantages of using exothermic reactions for hand warmers is that they keep your hands warm because they release thermal Energy to the surroundings.
11. What is the temperature change of the solution if the starting temperature was 20 degrees and the end temperature was -5 degrees. State if this is endothermic or exothermic.
    • The Energy change would be (-)15 degrees. This is an endothermic reaction.