1. Take another minute to compare you ideas with a neighbour
Learning objective:
demonstrate the distinction between exothermic and endothermic reactions
show how energy level diagrams can be used to summarize energy changes
28/04/2017
By yourself take a minute to come up with at least three examples of chemical changes involving an energy change.
Take another minute to compare you ideas with a neighbour
Share one example with the rest of the class.

2. Experiments 1 A test for water
Put a spatula measure of white copper sulfate powder into a test tube.
Add a few drops of water to the powder.
Watch what happens and feel the bottom of the test tube.
2 The sherbet mixture
In a dry test tube, mix one spatula measure of citric acid with one spatula measure of sodium hydrogencarbonate.
Add 2 cm3 water to the mixture.
3 Competing
Take about 5 cm3 copper sulfate solution in a test tube.
Add a small measure of powdered zinc.
Stir with a glass rod.

3. Results gives out energy (is exothermic)
Substances mixed
Observations
Does the mixture get hotter or colder?
Exothermic or endothermic?
gives out energy (is exothermic)
takes in energy (is endothermic)

4. Practical

5. Results gives out energy (is exothermic)
Substances mixed
Observations
Does the mixture get hotter or colder?
Exothermic or endothermic?
ammonium nitrate + water
anhydrous copper (II) sulfate + water
sodium hydrogen carbonate, citric acid and water
copper (II) sulfate + zinc
White powders; fizzes and dissolves
White powder; dissolves
Blue soln & grey solid; soln loses colour & solid darker/red
White powder turns blue; blue soln
Colder
Hotter
Colder
Hotter
Endothermic
Exothermic
Endothermic
Exothermic
gives out energy (is exothermic)
takes in energy (is endothermic)

6. Endothermic ammonium nitrate solid (NH4NO3 (s))
Diagram sheet
Endothermic
ammonium nitrate solid (NH4NO3 (s))
ammonium nitrate solution NH4+(aq) + NO3-(aq)
water (aq)
Energy taken in from the surroundings
ammonium nitrate soln (NH4+(aq) + NO3-(aq))
Energy taken in from the surroundings
ammonium nitrate solid (NH4NO3 (s)) + (aq)

7. Exothermic powdered zinc (Zn (s)) Energy released to the surroundings
zinc sulfate soln (ZnSO4(aq))
copper sulfate soln (CuSO4(aq))
powdered copper (Cu (s))
Zn (s) + CuSO4 (aq)
Energy released to the surroundings
Cu (s) + ZnSO4 (aq)

8. Draw energy level diagrams for the other two reactions
anhydrous copper (II) sulfate + water 
hydrated copper (II) sulfate
CuSO4 (s) + 5 H2O (l)  CuSO4.5H2O (s)
sodium hydrogen carbonate + citric acid 
sodium citrate + water + carbon dioxide
3 NaHCO3 (aq) + C3H5(COOH)3 (aq) 
C3H5(COONa)3 (aq) + 3 H2O (l) + 3 CO2 (g)

9. Exothermic Endothermic CuSO4 (s) + 5 H2O (l)
Energy released to the surroundings
CuSO4.5H2O (s)
C3H5(COONa)3 (aq) + 3 H2O (l) + 3 CO2 (g)
Endothermic
Energy taken in from the surroundings
3 NaHCO3 (aq) + C3H5(COOH)3 (aq)