Enthaply Changes

Question 1

What is the standard enthalpy change of neutralisation?

Answer 1

It is the energy change that accompanies the reaction of an acid by a base to form 1 mole of water, under standard conditions, with all reactants and products in their standard states.

Question 2

What is the standard enthalpy change of formation?

Answer 2

It is the the enthalpy change that takes place when one mole of a compound is formed from its elements, under standard conditions, with all products and reactants in the standard states.

Question 3

What is the standard enthalpy change that of combustion?

Answer 3

It is the enthalpy change that takes place when one mole of a substance reacts completely with oxygen, under standard conditions, with all reactants and products in standard conditions.

Question 4

What are the standard conditions?

Answer 4

• 100Ka Pressure
• 25C/298K Temperature
• 1mol/dm-3 Concentration

Question 5

What is the standard enthalpy change of reaction?

Answer 5

The standard enthalpy change of reaction is the enthalpy change that accompanies the reaction in the molar quantities shown in a chemical equation under standard conditions, with all the reactants and products in their standard states

Question 6

describe in terms of bond breaking and bond making what happens in an endothermic reaction.

Answer 6

Energy is absorbed to break bonds. Bond-breaking is an endothermic process.

Question 7

describe in terms of bond breaking and bond making what happens in an exothermic reaction

Answer 7

Energy is released when new bonds form. Bond-making is an exothermic process.

Question 8

What happens to the temperature in an exothermic reaction?

Answer 8

the temperature increases, energy is released to the surroundings

Question 9

What happens to the temperature in an endothermic reaction?

Answer 9

the temperature decreases, energy is absorbed