c.7 Energy changes

Question 1

What happens to energy in a chemical reaction?

Answer 1

It is conserved the amount of energy at the end of the reaction is the same as the amount of energy at the start

Question 2

What is an exothermic reaction?

Answer 2

A reaction in which energy is transferred to the surrounding so the temperature of the surrounding increases

Question 3

What are examples of exothermic reactions?

Answer 3

Combustion, oxidation, reactions and neutralisation

Question 4

What are everyday uses of exothermic reactions?

Answer 4

Self heating cans and neutralisation

Question 5

What is an endothermic reaction?

Answer 5

A reaction in which energy is transferred from the surroundings to the temperature of the surrounding decreases

Question 6

What are examples of endothermic reactions?

Answer 6

Thermal decomposition and reaction of citric acid and sodium hydrogen carbonate

Question 7

What are everyday uses of endothermic reactions?

Answer 7

Sports injury pack

Question 8

What is activation energy?

Answer 8

The minimum amount of energy that particles must have to react and the reacting particles collide with each other

Question 9

What are reaction profiles?

Answer 9

A diagram that can be used to show the relative energies of reactants and products. It shows the activation energy and the overall energy change of a reaction.

Question 10

What happens to bonds during a chemical reaction?

Answer 10

Energy is supplied to break bonds in the reactants and energy is released when bonds in the product or formed

Question 11

How can the overall energy change be calculated?

Answer 11

Calculate the difference between a sum of the energy needed to break the bonds in the reactant and the sum of energy release when bonds in the products are formed