Ch.13+18 - Heats Of Reaction, Equilibrium

Question 1

What is the the heat of reaction?

Answer 1

The heat of reaction (ΔH) is the heat energy released/absorbed when the number of moles of reactants indicated in the balanced equation completely describe the reaction.

Question 2

What is bond energy?

Answer 2

Bond energy is the amount of energy (kJ) needed to break 1 mole of bonds of the same type, all species being in the gaseous state.

Question 3

What is the the heat of combustion of a substance?

Answer 3

The heat of combustion of a substance is the heat change (kJ) when 1 mole of the substance is burned in excess O2.

Question 4

What is the heat of formation?

Answer 4

The heat of formation is the heat change (kJ) when 1 mole of a substance is formed from its elements in their standard states.

Question 5

State Hess’ law.

Answer 5

Hess’ law states that the heat change of a reaction depends only on the initial and final states of the reaction and is independent of the route by which the reaction may occur.

Question 6

What is chemical equilibrium?

Answer 6

Chemical equilibrium is the state in which the rate of the forward reaction equals the rate of the reverse reaction. It is said to be dynamic because, at equilibrium, the reactions are continuously occuring.

Question 7

What is Le Chatelier’s principle?

Answer 7

Le Chatelier’s principle states that when a system at equilibrium is subjected to a stress, the equilibrium shifts in such a way as to minimise the effect of that stress.

Question 8

Describe the reactions of the Haber process and the Contact process. Give catalysts.

Answer 8

N2 + 3H2 = 2NH3, Fe
2SO2 + O2 = 2SO3, V2O5