2.4 Chemical Reactions and Energy

Question 1

Exothermic reaction

Answer 1

Energy is transferred to the surroundings. The temperature of the surroundings increases.

Question 2

Exothermic reaction examples

Answer 2

Combustion neutralisation, oxidation

Question 3

Exothermic reactions uses

Answer 3

Self heating food cans outdoor handwarmers

Question 4

Exothermic reactions uses

Answer 4

Self heating food cans outdoor handwarmers

Question 5

Endothermic reactions

Answer 5

Energy is taken in from the surroundings
Temperature of the surroundings decreases

Question 6

Endothermic reactions examples

Answer 6

Thermal decomposition and electrolysis reactions

Question 7

Endothermic reactions uses

Answer 7

Ice packs to treat injuries

Question 8

Exothermic reactions every profile- where are the products compared to reactants

Answer 8

Lower energy level as energy is given out

Question 9

Endothermic reactions energy profile- products are there in relation to reactants

Answer 9

Higher energy level than reactants- energy is taken in

Question 10

Activation energy definition

Answer 10

Minimum energy needed for a reaction to occur- energy needed to break bonds

Question 11

WhatWhat determines the type of reaction

Answer 11

Energy released or taken in to form bonds

Question 12

Calculating energy changes steps

Answer 12

1. Add together the bond energies for all the bonds in the reactants- this is the energy in
2. Add together the bond energies for all the bonds in the products- this is energy out
3. Overall energy change = energy in➖energy out

Question 13

If reaction is Exothermic will energy change be positive or negative

Answer 13

Negative

Question 14

If reaction is endothermic will energy change be positive or negative

Answer 14

Positive