Enthalpy Definitions

Question 1

Standard enthalpy of formation

Answer 1

the enthalpy change when one mole of a substance is formed from its constituent elements under standard conditions, all reactants and products being in their standard states

Question 2

standard enthalpy of combustion

Answer 2

the enthalpy change when one mole of a substance is completely burnt in oxygen under standard conditions, all reactants and products being in their standard states

Question 3

Hess’ Law

Answer 3

the enthalpy change for a chemical reaction is the same whatever route is taken from reactants to products

Question 4

standard conditions

Answer 4

298K and 100kPa

Question 5

standard enthalpy of atomisation

Answer 5

the enthalpy change which accompanies the formation of one mole of gaseous atoms from the element in its standard state under standard conditions

Question 6

first ionisation energy

Answer 6

standard enthalpy change when one mole of gaseous atoms is converted into a mole of gaseous ions each with a single positive charge

Question 7

first electron affinity

Answer 7

standard enthalpy change when a mole of gaseous atoms is converted to a mole of gaseous ions, each with a single negative charge

Question 8

second electron affinity

Answer 8

pg259