Enthalpy Definitions

Question 1

Enthalpy of atomisation

Answer 1

The energy required to form one mole of gas from an element under STP

Question 2

Lattice enthalpy of formation

Answer 2

The energy released when one mole of an ionic solid is formed from its gaseous ions under STP

Question 3

Enthalpy of reaction

Answer 3

The enthalpy change when the molar quantities of reagents shown in an equation react according to that equation

Question 4

Enthalpy of formation

Answer 4

The enthalpy change when one mole of a compound is formed from its elements in their normal physical states under STP

Question 5

Enthalpy of combustion

Answer 5

The enthalpy change when one mole of a substance is completely burned in air/oxygen under STP

Question 6

Hess’ law

Answer 6

States that:
The total enthalpy change for a reaction is independent of the route taken, provided the initial and final conditions are the same

Question 7

STP

Answer 7

Stated temp and pressure:

298K and 1 atm pressure

Question 8

Average bond enthalpy

Answer 8

The average enthalpy change when one mole of a bond is broken into separate gaseous atoms of the element concerned [ALWAYS ENDO]

Question 9

Making bonds =

Answer 9

EXOTHERMIC

Question 10

Breaking bonds =

Answer 10

ENDOTHERMIC

Question 11

Enthalpy of neutralisation

Answer 11

The enthalpy change when one mole of water is formed by the neutralisation of a specified acid by a specified base under STP