Section 4

Question 1

What can you use bond energies to calculate?

Answer 1

Enthalpy change for a reaction.

Question 2

Enthalpy change =

Answer 2

total energy absorbed to break bonds - total energy released in making bonds.

Question 3

If the enthalpy change is negative what must the reaction be?

Answer 3

Exothermic.

Question 4

How do you work out the molar enthalpy change?

Answer 4

1. Calculate amount of energy transferred.

2. Find the moles = mass / Mr