energy changes 🔋

Question 1

examples of exothermic reactions

Answer 1

freezing, condensation, crystallisation, combustion, respiration, dilution of acids and alkalis

Question 2

examples of endothermic reactions

Answer 2

melting, boiling, evaporation, sublimation, dissolving ionic compounds, thermal decomposition, photosynthesis

Question 3

enthalpy change explanation in terms of bond breaking and bond forming

Answer 3

exothermic because energy released during bond forming in reactants is more than energy absorbed during bond breaking in products (vice versa)

Question 4

define bond energy

Answer 4

bond energy is the energy absorbed to break one mole of covalent bonds (kJ/mol)

Question 5

define activation energy

Answer 5

activation energy is the minimum amount of energy that reacting particles must possess in order for a chemical reaction to occur