5. Chemical Energetics

Question 1

Standard enthalpy change of reaction

Answer 1

The enthalpy change when the number of moles of reactants as specified in the balanced equation react together under standard conditions

Question 2

Standard enthalpy change of formation

Answer 2

The enthalpy change when one mole of a compound is formed from its constituent elements in their standard states under standard conditions

Question 3

Standard enthalpy change of combustion

Answer 3

The enthalpy change when one mole of a substance completely burns in oxygen under standard conditions

Question 4

Standard enthalpy change of hydration of an anhydrous salt

Answer 4

The enthalpy change when one mole of a hydrated salt is formed from one mole of the anhydrous salt under standard conditions

Question 5

Standard enthalpy change of hydration

Answer 5

The enthalpy change when one mole of gaseous ions become aqueous ions under standard conditions

Question 6

Standard enthalpy change of solution

Answer 6

The enthalpy change when one mole of solute is dissolved in a large amount of water to form an infinitely dilute solution under standard conditions

Question 7

Standard enthalpy change of neutralisation

Answer 7

The enthalpy change when one mole of water is formed when an acid reacts with an alkali under standard conditions

Question 8

Standard enthalpy change of atomisation

Answer 8

The enthalpy change when one mole of gaseous atoms is formed from its element in its standard state under standard conditions

Question 9

Hess’ Law

Answer 9

The enthalpy change to convert reactants into products is independent of the routes taken, provided the initial and final conditions are the same