Chemical Energy

Question 1

It is essential that industrial chemists can?

Answer 1

Be able to calculate the amount of heat given out or taken in by each chemical reaction in a chemical process

Question 2

What do endothermic reactions require?

Answer 2

Require heat to be supplied, which incurs costs

Question 3

What happens to the heat produced during exothermic reactions?

Answer 3

Needs to be removed to avoid the temperature rising too high

Question 4

What happens to the heat produced during endothermic reactions?

Answer 4

Not wasted and can be used elsewhere in a process, eg. to heat catalysts

Question 5

Describe the enthalpy of combustion

Answer 5

Enthalpy change when 1 mole of a substance burns completely in oxygen

Question 6

Enthalpy of combustion is always?

Answer 6

Exothermic

Question 7

How are enthalpy changes calculated?

Answer 7

Eh=mc delta t

Question 8

What is the enthalpy of reaction measured in?

Answer 8

KJ.mol -1

Question 9

What can enthalpies of formation be used to calculate?

Answer 9

Enthalpies of other reactions

Question 10

What method can you use to calculate enthalpy changes?

Answer 10

Hess’s Law

Question 11

Describe the mean molar bond enthalpy

Answer 11

The average bond enthalpy for bonds that exist in different molecular environments

Question 12

Describe the enthalpy of solution

Answer 12

Enthalpy change when 1 mole of that substance dissolved completely in water

Question 13

Describe the enthalpy of neutralisation

Answer 13

Enthalpy change when 1 mole of water is formed during an acid/alkali neutralisation reaction

Question 14

What is the difference between bond enthalpy and mean bond enthalpy

Answer 14

Mean bond enthalpy must refer to an average energy and to a number of compounds whilst bond enthalpy must relate to one compound/diatomic molecule