enthalpy

Question 1

What is enthalpy?

Answer 1

The heat content that is stored in a chemical system.

Question 2

What is the conservation of energy in terms of an exothermic reaction?

Answer 2

-Energy transferred from system goes to the surroundings.
- The temperature of the surroundings increase as they gain energy.

Question 3

What is the conservation of energy like in terms of endothermic reactions?

Answer 3

• Energy transferred from surroundings goes to the system.
• Chemical system takes in the heat energy from the surroundings.
• Temperature of the surroundings decreases as they lose energy.

Question 4

What is activation energy?

Answer 4

Minimum energy required for a reaction to take place.

Question 5

What are the standard conditions?

Answer 5

pressure -100 KPa
temperature- 298K (25 degrees celsius)
concentration - 1 mol dm-3

Question 6

What is enthalpy change of reaction?

Answer 6

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

Question 7

Standard enthalpy change of formation.

Answer 7

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

Question 8

Standard enthalpy change of combustion.

Answer 8

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 their standard states.

Question 9

Standard enthalpy of neutralisation.

Answer 9

The enthalpy change that accompanies the reaction of an acid by a base to form one mole of H20, under standard conditions, with all reactants and products in their standard states.

Question 10

What is bond enthalpy?

Answer 10

Energy required to break one mole of a covalent bond averaged over a range of environments.