topic 13: energetic 2

Question 1

lattice energy defintion

Answer 1

energy change when ONE MOLE of an ionic compound is formed from its GASEOUS ions

Question 2

enthalpy change of atomisation defintion

Answer 2

enthalpy change when 1 mole of gaseous atoms is formed from the element in its standard state

Question 3

electron affinity

Answer 3

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

Question 4

which lattice enthalpy is strongest

Answer 4

the MOST exothermic

Question 5

2 things lattice enthalpy depend on

Answer 5

• charge on ion (the higher the stronger)
• the size (the smaller the stronger)

Question 6

down a grorup, for the same anion the LE becomes

Answer 6

LESS NEGATIVE

Question 7

explain difference between theoretical and experimental

Answer 7

• theoretical assumes 100% ionic bonding
• in experimental, not 100% ionic
• cation has small IR and high charge, anion has large IR, so cation polarises anion
• so bonding has some covalent character
• so LE is more exothermic

Question 8

what increases the covalent character

Answer 8

• polarising power of cation: (if its small, if it has a high charge)
• the size of the anion; the larger it is the more easily distorted

Question 9

enthalpu change of solution

Answer 9

enthalpy change when one mole of an ionic solid dissolves to form aqueous ions
eg nacl(s) + aq -> na+(aq) + cl-(aq)

Question 10

enthalpy chnage of hydration

Answer 10

enthlapy change when one mole of gaseous ions become hydrated

Question 11

enthalpy od hydration is always

Answer 11

exothermic

Question 12

enthalpy of solution is

Answer 12

enthalpy of hydration - lattic enthalpy

Question 13

what delta h solution is the most solutble

Answer 13

the most exo

Question 14

effect of ionic charge and size on enthalpy of hydration

Answer 14

• the higher the charge and the smaller the ion, the more negative the hydration enthalpy