What happens to total energy during a chemical reaction?
Energy is transferred between the reacting chemicals and the surroundings, but total energy is conserved.
AQA GCSE Combined Science: Trilogy (8464) — Chemistry — Foundation · 5.5.1.1
Revise AQA GCSE Combined Science: Trilogy (8464) — Chemistry — Foundation specification point 5.5.1.1, Energy transfer during exothermic and endothermic reactions, with free active-recall flashcards. Flip through the set or review every question and answer below.
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What happens to total energy during a chemical reaction?
Energy is transferred between the reacting chemicals and the surroundings, but total energy is conserved.
What energy transfer and surroundings temperature change identify an exothermic reaction?
Energy is transferred to the surroundings, which become warmer.
What energy transfer and surroundings temperature change identify an endothermic reaction?
Energy is taken from the surroundings, which become cooler.
How do the stored energies of the products and reactants compare in an exothermic reaction?
The products store less energy than the reactants by the amount transferred to the surroundings.
How do the stored energies of the products and reactants compare in an endothermic reaction?
The products store more energy than the reactants by the amount taken in from the surroundings.
What are three typical examples of exothermic reactions?
Combustion, many oxidation reactions, and neutralisation.
What are two typical examples of endothermic reactions?
Thermal decomposition and the reaction of citric acid with sodium hydrogencarbonate.
How can an exothermic reaction warm its surroundings?
It releases energy to its surroundings.
How can an endothermic reaction cool its surroundings?
It absorbs energy from its surroundings.
What are two applications of exothermic reactions for warming?
Self-heating cans and hand warmers.
What is an application of an endothermic reaction for cooling?
Some sports injury packs.
How should the suitability of a reaction for heating or cooling be judged?
Use the available information about its heating or cooling effect: it must transfer enough energy for the intended temperature change. Enthalpy calculations are not required.