2.4 CHEMICAL REACTIONS AND ENERGY

Question 1

WHAT IS AN EXOTHERMIC REACTION?

Answer 1

A reaction that produces heat

Question 2

WHAT ARE SOME EXAMPLES OF EXOTHERMIC REACTIONS?

Answer 2

• combustion
• neutralisation

Question 3

WHAT IS AN ENDOTHERMIC REACTION?

Answer 3

A reaction that takes heat in

Question 4

WHAT ARE SOME EXAMPLES OF ENDOTHERMIC REACTIONS?

Answer 4

• electrolysis
• thermal decomposition

Question 5

DOES THE PRODUCT OR THE REACTANT HAVE THE HIGHER ENERGY IN AN EXOTHERMIC REACTION?

Answer 5

Reactant

Question 6

DOES THE PRODUCT OR THE REACTANT HAVE THE HIGHER ENERGY IN AN ENDOTHERMIC REACTION?

Answer 6

Product

Question 7

WHAT VALUE DOES THE OVERALL ENERGY CHANGE HAVE IN AN EXOTHERMIC REACTION?

Answer 7

Negative

Question 8

WHAT VALUE DOES THE OVERALL ENERGY CHANGE HAVE IN AN ENDOTHERMIC REACTION?

Answer 8

Positive

Question 9

WHAT ARE THE THREE STEPS FOR BOND CALCULATIONS?

Answer 9

1) calculate total energy needed to break all bonds in reactants (energy in)
2) calculate total energy released when product bonds are formed (energy out)
3) energy change = energy in + energy out

IMPORTANT NOTE:
- energy in = positive
- energy out = negative