Therodynamics

Question 1

What is atomisation enthaply and what type of reaction is it

Answer 1

The energy needed to produce one mole of free gaseous atoms of that atom in standard conditions and in its standard states and it’s endothermic

1/2Cl2(g)->Cl(g)

Na(s)->Na(g)

Question 2

What is first ionisation energy and what type of reaction is it

Answer 2

The amount of energy needed to remove one electron from each mole of free gaseous atoms of that element to form positive ions it’s exothermic

Na(g)->NA+(g)+e-

Question 3

What is first electron affinity and what type of reaction is it

Answer 3

The energy change when one electron is added to each of a mole of free gaseous atoms of that element for negative ions it’s exothermic

Cl(g)+e->Cl-(g)

Question 4

What is second ionisation energy of an element

Answer 4

The energy needed to remove one electron from each mole of free positive ions of that element

Mg+(g)->Mg2+(g)e-

Question 5

What is second electron affinity of an atom and what type of reaction is it

Answer 5

Its the energy change when one mole of electrons are added to a mole of gaseous atoms each with a single negative charge to form ions each with 2nd negative charges

It’s exothermic

O-(g)+e->O2-(g)

Question 6

What is lattice enthalpy of formation

Answer 6

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

Na+(g)+Cl-(g)->Nacl(s)

Question 7

What is enthaply of lattice dissociation and state the type of reaction it is

Answer 7

Is standard enthalpy change when one mole of solid ionic compound is dissociated into its gaseous ions

It’s endothermic (+)

Question 8

What is enthaply of hydration

Answer 8

Its the standard enthalpy change when water molecules surround one mole of gaseous ions and become aqa ions

Na+(g) +aq->Na+(aq)

Question 9

What is enthaply of solution

Answer 9

Standard enthalpy change when one mol of an ionic compound dissolves completely in water to form a solution in which don’t interact with one another

NACL-NACl(aq)

Question 10

What reaction does this represent

Mg (s)->Mg (g)

Answer 10

Standard enthalpy of atomisation

Question 11

What reaction does this represent

Mg(g)->Mg+ (g)+e-

Answer 11

First ionisation energy

Question 12

What is mean bond enthaply

Answer 12

Energy change when I mole of gaseous molecules each break a covalent bond which is averaged over a range of compounds

Question 13

Why are atomisation enthalpies endothermic

Answer 13

As bonds in the element need to be broken

Question 14

Why are second ionisation energies more endothermic than first ionisation energies

Answer 14

As there is less repulsion between the remaining electrons in the ion so more energy is needed to remove the electrons

Question 15

Why are second electron affinities endothermic

Answer 15

As the incoming electron is repelled by the negative charge on the ion so the value is positive

Question 16

Why are lattice enthalpies of formation negative and why are lattice enthalpies of dissociation positive

Answer 16

Ionic bonds are being formed so it’s exothermic

Ionic bonds are being broken so it’s endothermic

Question 17

State the two ways to work amount enthaply change of solution

Answer 17

Hydration - lattice of formation

Hydration +lattice of dissociation

Question 18

What is entropy and how do you work it out

Answer 18

It’s the degree of disorder of a system higher degree the more stable it is

Products - reactant

Question 19

State what will become of the reaction when entropy is positive or negative

Answer 19

If entropy is positive the reaction is more likely

If it’s negative it’s less likely to occur

Question 20

State the free energy equation and what each symbol stands for

Answer 20

G=H-TS

G is change in free energy
H is change in enthaply
A change in entropy

Question 21

If G is positive what will happen

Answer 21

The reaction will not proceed

Question 22

If G is negative what will happen

Answer 22

The reaction will occur

Question 23

What will happen to the reaction of enthaply is negative and entropy is positive

Answer 23

The reaction is spontaneous at all temperature because theirs more disorder due to increasing entropy

Question 24

If enthaply is positive and entropy is negative what will happpen

Answer 24

The reaction won’t be spontaneous at any temperature

Question 25

What does it mean for the reaction if both entropy and enthalpy are positive

Answer 25

It means the reaction will be spontaneous above a certain temperature

Question 26

What does it mean if both enthaply and entropy are both negative

Answer 26

The reaction will only be spontaneous below a certain temperature

Question 27

How would you work out temperature in Gibbs free energy

Answer 27

T=H/S

Question 28

Which types of lattices have the higher lattice enthalpies

Answer 28

Smaller lattices this is because the cations and anions are closer together so they attract together more closely

Question 29

How is entropy worked out

Answer 29

Products - reactants

Question 30

In Gibbs free energy how is entropy worked out

Answer 30

Enthaply/Temperature

Question 31

What is the perfect ionic model

Answer 31

It’s spherical shaped with only electrostatic forces of attractions with ionic bonds

Question 32

What causes differences with the theoretical and experimental lattice enthalpies and what is the cause of this

Answer 32

When a compound shows covalent character which is caused by polarisation

Question 33

State the type of reaction hydration enthalpies are and what factor cause some elements to have higher hydration enthalpies than others and why

Answer 33

They are exothermic reactions

They higher the charge density the greater the hydration enthalpy this id because ions attract water molecules more strongly

Question 34

What causes polarisation

Answer 34

The negative ion because distorted and more covalent because of that metal cation causes polarisation

Question 35

What tendencies cause covalent character

Answer 35

Small positive ion-because

Positive ion having multiple charges

Negative ion being large meaning outer shell electrons to be less attracted

Negative ions has multiple negative charges

Question 36

State why when a solid dissolves it will be more spontaneous

Answer 36

As entropy increases because theirs more disorder

Increases entropy means more particles

This makes G more negative

Question 37

What does this represent

CL2->2Cl

Answer 37

Bond disassociation so we divide by 2

Question 38

Why is enthaply hydration exothermic

Answer 38

As bonds are made between ions and water which releases energy

Question 39

When will substances have zero entropy

Answer 39

When temperature is absolute 0