Energy Changes. Some reactions release heat energy. Give 2 examples. Where might these reactions be useful Name a reaction in your body that releases heat energy. What do we call reactions that release heat energy. Why do you think some reactions release heat energy?

BIG PICTURE Why are Fossil Fuels so fantastic and how do we find alternatives for when they run out?

You will be learning about reactions that give out energy. By the end of the lesson you will be able to: Grade 6– Describe the difference between exothermic and endothermic reactions and categorize different reactions. Grade 7 – Explain why some reactions release energy. Grade 8 – Explain what happens in a chemical reaction in terms of bonds breaking and making and how this results in some reactions some reactions giving out Energy and others taking in Energy.

Exothermic reactions. Youtube: Exothermic and Endothermic Reactions

Endothermic Reactions

Results Reactants Always add liquid first Temperature (o C) Start end change hydrochloric acid and sodium hydroxide hydrochloric acid and anhydrous sodium carbonate ethanoic acid and solid ammonium carbonate distilled water and solid ammonium nitrate hydrochloric acid and magnesium ribbon.

Grade 6 In your own words, describe what exothermic and endothermic reactions are and give examples of each. Using the experiments

Energy is contained within chemical bonds. These bonds must be broken Energy is contained within chemical bonds. These bonds must be broken. This requires energy

New bonds must now be made. This process releases energy.

Energy level profile Energy Extent of reaction (time) Copy and complete the diagram. Explain in your own words what is happening at each stage. Include ideas why exothermic reactions release heat energy (grade 9) Energy reactants Extent of reaction (time)

Demonstrate Methane Bubbles

Grade 7 and 8 Under you diagram, explain in terms of bond energies why the exothermic reaction of burning methane releases heat energy.