standard enthalpy changes

Question 1

Define ∆fHᶱ (standard enthalpy change of formation)

Answer 1

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

Question 2

Define ∆cHᶱ (standard enthalpy change of combustion)

Answer 2

enthalpy change when one mole of a substance is burned completely in oxygen, under standard conditions
-produces CO2 and H2O
- always -ve as reactions are exothermic

Question 3

Define ∆nHᶱ (standard enthalpy change of neuralization)

Answer 3

enthalpy change when an alkali and acid in the equation neutralise each other to form one mole of water, under standard conditions