Thermodynamics

Question 1

Enthalpy change

Answer 1

the heat energy change at constant pressure

Question 2

standard enthalpy of formation

Answer 2

enthalpy change when one mole of a substance is formed from its elements under standard conditions, with all substances in their standard state

Question 3

standard enthalpy of combustion

Answer 3

enthalpy change when one mole of substance is completely combusted in excess oxygen under standard conditions, with all substances in their standard state

Question 4

mean bond enthalpy

Answer 4

enthalpy change when one mole of a given covalent bond is broken, averaged over a range of compounds

Question 5

bond dissociation enthalpy

Answer 5

enthalpy change to break the bond in one mole of gaseous molecules to form gaseous atoms

Question 6

standard enthalpy of atomisation

Answer 6

enthalpy change for the formation of one mole of gaseous atoms from the electrons in its standard state

Question 7

first ionisation energy

Answer 7

enthalpy change when one mole of electrons is removed from one mole of gaseous atoms to form one mole of gaseous 1+ ions

Question 8

second ionisation energy

Answer 8

enthalpy change when one mole of electrons is removed from one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions

Question 9

first electron affinity

Answer 9

enthalpy change when one mole of electrons is added to one mole of gaseous atoms to form one mole of gaseous 1- ions

Question 10

second electron affinity

Answer 10

enthalpy change when one mole of electrons is added to one mole of gaseous 1- ions, to form one mole of gaseous 2- ions

Question 11

lattice formation enthalpy

Answer 11

enthalpy change when one mole of a solid ionic compound is formed from its gaseous ions

Question 12

lattice dissociation enthalpy

Answer 12

enthalpy change to separate one mole of solid ionic compound into its gaseous ions

Question 13

Gibbs free energy (and in relation to graphs)

Answer 13

Question 14

entropy

Answer 14

measure of disorder in a system
delta S = total products - total reactants

Question 15

enthalpy of solution

Answer 15

enthalpy change when 1 mol of solid dissolves in water to form aq ions

Question 16

enthalpy of hydration

Answer 16

enthalpy change when 1 mol of gaseous ions become aq ions
ectothermic

Question 17

Features of perfect ionic model

Answer 17

all ions are perfect spheres with 100% ionic attraction

Question 18

if experimental value is same as theoretical

Answer 18

there’s no covalent character

Question 19

will born haber values be smaller than the perfect ionic model

Answer 19

no

Question 20

with covalent character the ionic bond is

Answer 20

stronger