entropy and enthalpy

Question 1

give the definition for lattice enthalpy

Answer 1

the energy released when one mole of an ionic compound/lattice is formed from its gaseous ions

Question 2

define enthalpy change of formation

Answer 2

the enthalpy change when 1 mole of a compound is formed from its elements in their standard states

Question 3

are lattice enthalpies exothermic or endothermic and why?

Answer 3

exothermic - involves the formation of bonds which releases energy

Question 4

is enthalpy change of formation endo or exothermic

Answer 4

can be both

Question 5

define enthalpy change of atomisation

Answer 5

the energy required to form 1 mole of gaseous atoms from an element in its standard state

Question 6

is enthalpy change exo or endo thermic

Answer 6

always endothermic

Question 7

define enthalpy change of first ionisation energy

Answer 7

the energy required to remove 1 mole of electrons from one mole of gaseous atoms to form 1 mole of gaseous ions with a +1. charge

Question 8

is enthalpy change of first ionisation energy exo or endothermic

Answer 8

endothermic

Question 9

define enthalpy change of second ionisation energy

Answer 9

the energy required to remove 1 mole of electrons from one mole of gaseous ions with a 1+ charge to form 1 mole of gaseous ions with a 2+ charge

Question 10

define enthalpy change of first electron affinity

Answer 10

energy released when 1 mole of gaseous atoms gain 1 mole of electrons to form 1 mole of gaseous ions with a 1- charge

Question 11

is enthalpy change of electron affinity endo or exo

Answer 11

exothermic

Question 12

define enthalpy change of second electron affinity

Answer 12

the enthalpy change when 1 mole of gaseous ions gain 1 mole of electrons to form 1 mole of gaseous ions with a 2- charge.

Question 13

what is the order for constructing a born harber cycle

Answer 13

enthalpy change formation —–>
enthalpy change of atomisation —> enthalpy change lattice enthalpy –>
enthalpy change electron affinity

Question 14

define enthalpy change of solution

Answer 14

the enthalpy change when one mole of an ionic compound dissolves in water

Question 15

is enthalpy change of solution endo or exothermic

Answer 15

endothermic - breaking bonds

Question 16

define enthalpy change of hydration

Answer 16

energy released when one mole of gaseous ions dissolves in water

Question 17

is enthalpy change of hydration exo or endo

Answer 17

exothermic

Question 18

how do u calculate enthalpy change of solution

Answer 18

• (lattice enthalpy) + (enthalpy change of hydration)

Question 19

what are the 2 factors affecting lattice enthalpy

Answer 19

charge and ionic radius

Question 20

what is entropy

Answer 20

measure of disorder in a system,
highly disordered = high entropy

Question 21

as temperature increases what happens to entropy

Answer 21

increases, as particles have higher energy so become more disordered

Question 22

how do u calculate entropy change

Answer 22

(sum of products) - ( sum of reactants)k

Question 23

what are the limitations of predictions made by delta G

Answer 23

rate is very slow as high activation energy

non standard conditions may be used

Question 24

what is the definition for standard entropy of a substance

Answer 24

the entropy of 1 mol of a substance in JK-1 mol-1 under standard conditions (1 atm 298K)