Energetics

Question 1

Exothermic reaction

Answer 1

Reaction that transfers energy to surroundings, so temperature of surroundings increases e.g combustion, many oxidation reactions e.g Sodium + Water, respiration, neutralisation, displacement, everyday use of exothermic reactions e.g hand warmers, delta H is negative, energy released from forming new bonds is greater than energy needed to break existing bonds

Question 2

Endothermic

Answer 2

Reaction that takes in energy from surroundings, so temperature of surroundings decreases e.g thermal decompositions + reaction of citric acid + sodium hydrogencarbonate, photosynthesis, everyday use of endothermic reactions e.g some sports injury packs (ice pack), delta H is positive, energy needed to break existing bonds is greater than energy released from forming new bonds

Question 3

Activation energy

Answer 3

Minimum amount of energy that particles must have to react

Question 4

Two requirements for a chemical reaction to react

Answer 4

1. Activation energy
2. Particles colliding with each other

Question 5

Energy change of a reaction

Answer 5

Delta H = Bonds broken - Bonds made