Chemistry thermodynamics definitions

Question 1

ΔHθr standard enthalpy change of reaction

Answer 1

The enthalpy change when the reactants in the stoichiometric equation react to form the products under standard conditions

Question 2

ΔHθf standard enthalpy change of formation

Answer 2

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

Question 3

ΔHθc standard enthalpy change of combustion

Answer 3

The enthalpy change when one mole of a substance is burnt in excess oxygen under standard conditions

Question 4

ΔHθneut standard enthalpy change of neutralisation

Answer 4

The enthalpy change when one mole of water is formed by reacting an acid and an alkali under standard conditions

Question 5

standard enthalpy change of reaction…exothermic or endothermic?

Answer 5

both

Question 6

standard enthalpy change of formation…exothermic or endothermic?

Answer 6

both

Question 7

standard enthalpy change of combustion…exothermic or endothermic?

Answer 7

exothermic

Question 8

standard enthalpy change of neutralisation…exothermic or endothermic?

Answer 8

exothermic