C7 Energy Changes

Question 1

Why can’t energy be created or destroyed?

Answer 1

Because of the conservation of energy

Question 2

In a chemical reaction what do we know has happened?

Answer 2

Energy has been transfered

Question 3

What is an exothermic reaction?

Answer 3

A reaction where energy is given out to it’s surroundings (nearly always heat)

Question 4

Give an example of an exothermic reaction?

Answer 4

Burning fuels (combustion)

Many oxidation reactions are exothermic as well has neutralising reactions

Question 5

What are exothermic reactions used for today?

Answer 5

Hand warmers

Self heating cups (hot chocolate..)

Question 6

Explain hamd warmers??

Answer 6

?

Question 7

What is an endothermic reaction?

Answer 7

A reaction which takes in energy

Usualy heat with a fall in temprature

Question 8

Are the majority of reactions exothermic or endothermic?

Answer 8

Exothermic

Question 9

Give an example of an endothermic reaction?

Answer 9

Photosynsis

Thermal decompesition

Question 10

What is a common use of endothermic reactions today?

Answer 10

Sports injury pacts (cool packs)

Question 11

Explain cool packs??

Answer 11

?

Question 12

What is activation energy?

Answer 12

The minimum enegy needed to start an reaction by causing particles to collide with each other and react

Question 13

Describe an exothermic graph?

Answer 13

The reactant has a little increase in enegy which is the actibation energy and then drops down and releases energy

Question 14

Using a graph what gives you the amount of energy lost or gained?

Answer 14

The difference in hight from the reactant to the product shows how much energy is lost or gained

Question 15

Describe an endothermic graph?

Answer 15

The reactant starts increasing and then drops off a bit but overall the product energy is higher than the initial energy.

Question 16

What is the energy increase/decrease measured in?

Answer 16

J/mol

Question 17

How are bonds brocken?

Answer 17

When they gain energy

Question 18

Is bond breaking an exothermic or endothermic prosses?

Answer 18

Endothermic

Question 19

Is bond making an exothermic or endothermic prosses?

Answer 19

Exothermic

Question 20

How are bond made?

Answer 20

Energy is released

Question 21

Describe an exothermic reaction in terms of bonds?

Answer 21

Energy is transfered into the chemical to break the bonds however after that more energy is given out to make new bonds. These new bonds will be stronger than the originals

Question 22

Describe an endothermic reaction in terms of bonds?

Answer 22

Energy is transfered into the chemical to break the bonds however after that less energy is given out to make new bonds. These new bonds will be weaker than the originals.