Which statement about an exothermic reaction is correct?
Answer and explanation
Correct answer: B. The products have less energy than the reactants and heat is given out to the surroundings
- Step 1: In an exothermic reaction the energy released on forming bonds is greater than the energy used to break bonds.
- Step 2: The extra energy goes to the surroundings, so the temperature rises.
Answer
The products have less energy than the reactants and heat is given out to the surroundings.
Why not the others: The products have more energy than the reactants and heat is taken in from the surroundings: describes an endothermic reaction. The reactants and products have the same energy and heat is given out: energy would not be conserved. The products have less energy than the reactants and heat is absorbed: energy lost by the reaction goes out, not in.
Practise more Energetics.
Free questions with an explanation for every one, and full timed ESAT (Engineering and Science Admissions Test) mock tests.