Enthalpy Change Definitions

Question 0

Standard Enthalpy Change Of Combustion (ΔHc)

Answer 0

The enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditions

Question 1

Standard Enthalpy Change of Reaction(ΔΗr)

Answer 1

The enthalpy change that accompanies a reaction in the molar quantities expressed in a chemical equation under standard conditions

Question 2

Standard Enthalpy Change of Formation (ΔHf)

Answer 2

The enthalpy change that takes place when one mole of a compound is formed from its constituent elements under standard conditions

Question 3

What are standard conditions?

Answer 3

298K (25 deg.) and 1 atmospheric pressure (100/101kPa)

Question 4

What is Hess’ Law?

Answer 4

States that, If a reaction can take place by more than one route and the initial and final conditions are the same, the total enthalpy change is the same for each route