Exothermic reactions
2 marks · HardA student says that 'all reactions which produce heat and raise the temperature are exothermic.' Give one example of a reaction that is exothermic, and explain how the energy changes in this type of reaction.
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Also accept: Combustion reactions (e.g., burning methane), metal and acid reactions, neutralisation, displacement; explanation should note energy/heat released to surroundings; Burning magnesium, with explanation that energy is released as heat
Common mistakes: Giving an endothermic process; Not explaining how energy is transferred
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Marking points
B1 · 1 mark · Gives a valid example of an exothermic reaction (e.g., combustion, metal + acid, neutralisation, displacement)
B2 · 1 mark · Explains that energy is released to the surroundings (as heat) and temperature rises
Worked solution
An example is the reaction of sodium hydroxide with hydrochloric acid. (B1)
Energy is released to the surroundings as heat, causing the temperature to increase. (B2)