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Energetics, Rates and Redox
Quick questions on Exothermic and endothermic reactions: N(A)-Level Chemistry
6short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What are exothermic reactions?Show answer
An exothermic reaction gives out energy to the surroundings, usually as heat. You can tell because the temperature rises. Burning fuels, neutralising an acid with an alkali, and most displacement reactions are exothermic. Because energy leaves the chemicals, the products store less energy than the reactants.
What are endothermic reactions?Show answer
An endothermic reaction takes in energy from the surroundings. You can tell because the temperature falls (the mixture feels cold). Dissolving some salts in water, and thermal decomposition (heating a compound to break it down), are endothermic. Because energy enters the chemicals, the products store more energy than the reactants.
What are energy level diagrams?Show answer
An energy level diagram shows the energy of the reactants and products as two horizontal lines:
What is q1?Show answer
A reaction causes the temperature of a solution to fall. State whether it is exothermic or endothermic. [1 mark]
What is q2?Show answer
State whether breaking bonds takes in or gives out energy, and do the same for making bonds. [2 marks]
What is q3?Show answer
On an energy level diagram for an exothermic reaction, state whether the products are higher or lower than the reactants, and why. [2 marks]
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