Topic 7- Heat and energy changes

Question 1

What happens in an endothermic reaction?

Answer 1

• More energy is taken in (to break stable bonds)
• BREAKS BONDS
• Than given out (making bonds, they are more unstable)

Question 2

What happens in an exothermic reaction?

Answer 2

• Heat is give out
• MAKES BONDS
• Unstable bonds become more stable giving out heat

Question 3

What type of reaction is salt dissolving in water?

Answer 3

Endothermic

Question 4

What type of reaction is neatralisation?

Answer 4

Exothermic

Question 5

What type of reaction is displacement ?

energy wise

Answer 5

Exothermic

Question 6

What type of reaction is precipitation ?

Answer 6

Exothermic or endothermic

Question 7

Describe an endothermic energy graph

Answer 7

• Rises (activation energy)
• Decreases slightly

Question 8

Describe an exothermic energy graph

Answer 8

• Rises (activation energy)
• Drops rapidly (energy given out)

Question 9

How to calculate the energy change?

Answer 9

• Work out the energy needed in (broken bonds)
• Work out the energy given out (made bonds)
• Find the difference
• If the difference is negative it is endothermic

Question 10

What is activation energy?

Answer 10

• The minimum energy needed for a reaction to occur