Which statement correctly describes the quantity known as the standard enthalpy of…
CHEMISTRY · Single correct · A Level · Chemistry · Energetics · Energetics
Problem
Which statement correctly describes the quantity known as the standard enthalpy of formation, ΔHf∘, for a substance at 298K and 1atm?
(a) It is the enthalpy change when one mole of the substance decomposes completely into its constituent elements under standard conditions.
(b) It is the enthalpy change when one mole of the substance is produced from its constituent elements in their most stable forms under standard conditions.
(c) It is the enthalpy absorbed when one mole of the substance combusts completely in excess oxygen to form CO2 and H2O under standard conditions.
(d) It is the enthalpy change when one mole of gaseous atoms of the constituent elements combine to form the substance under standard conditions.