T7 YR11 - Energy changes

Question 1

What is an exothermic reaction?

Answer 1

Gives out energy to surroundings, reaction components will increase temperature

Question 2

What are 2 exothermic reactions?

Answer 2

Combustion and neutralisation

Question 3

Do products have more or less energy than reactants in an exothermic reaction?

Answer 3

Less energy

Question 4

What is an endothermic reaction?

Answer 4

Reaction takes in energy, reaction components will decrease in temperature

Question 5

Do products have less or more energy than reactants in an endothermic reaction and why?

Answer 5

More because they have the taken in energy in the reaction

Question 6

Give examples of endothermic reactions?

Answer 6

Electrolysis, photosynthesis, heat (calcium carbonate)

Question 7

Give uses of exothermic reactions?

Answer 7

Hand warmed and heat packs that are disposable, using iron and oxygen to generate energy that is iron oxide

Question 8

Give another use of exothermic reactions?

Answer 8

Self heating coffee - calcium oxide and water
Reusable hand warmer - crystals solidify - heat

Question 9

Uses of endothermic reactions?

Answer 9

Disposable cold packs - ammonium nitrate + water and energy to give off ammonium nitrate, adding water breaks up the ions which takes in energy and cools surroundings
Extra electricity in electrolysis used to electrolyse water for hydrogen gas

Question 10

What is the reaction profile of an exothermic reaction?

Answer 10

Reactants higher than products and activation energy and heat evolved

Question 11

What is the reaction profile of an endothermic reaction?

Answer 11

Products are higher than reactants, activation energy and heat taken in

Question 12

What is the definition of activation energy?

Answer 12

Minimum amount of energy needed to start up a reaction

Question 13

What is the energy change calculation?

Answer 13

Energy of bonds broken - energy of bonds made