Thermodynamics Flashcards

1
Q

What are the 2 types of lattice enthalpy

A

Latice enthalpy of formation and dissociation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the difference between lattice enthalpy of formation and dissociation

A

Lattice enthalpy of dissociation is positive
Lattice enthalpy of formation is negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the lattice enthalpy of formation

A

The standard enthalpy change when one mole of solid ionic compound is formed from its gaseous ions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the lattice enthalpy of dissociation

A

The standard enthalpy change when one mole of solid ionic compound dissociated into its gaseous ions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is ionisation energy

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the enthalpy of formation

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the enthalpy of atomisation

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Bond dissociation enthalpy vs Enthalpy of atomisation

A

Bond dissociation - one mole of a bond is broken to give separated ions
Atomisation - Enthalpy change accompanying the formation of 1 mole of gaseous ions

Therefore the ΔA in Cl will be half the enthalpy of bond dissociation energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is mean bond enthalpy

A

Enthalpy change to break 1 mol of bonds

Averaged over a range of compounds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is electron affinity

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is enthalpy of hydration

A

The standard enthalpy change when water molecules surround one mole of gaseous ions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How do you edit a born haber cycle if atoms are diatomic

A

Multiply their enthalpies by 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What affects how large the lattice enthalpy of formation is

A

The size of the positive and negative ions
The bigger the ions, the smaller the lattice enthalpies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why is ΔΗ not sufficient for explaining feasible change

A

Depends on the sign of ΔG. If it is negative, the reaction is feasible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the symbol for entropy

A

ΔS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does increasing entropy mean

A

Increasing disorder

17
Q

What does reaction feasibility depend on

A

The balance of entropy and enthalpy

18
Q

What is the equation for Gibbs free energy

A

ΔG = ΔH - TΔS

ΔG = Gibbs free energy
ΔH = Change in enthalpy
T = temp in kelvin
ΔS = Change in entropy

19
Q

What is the formula for ∆S

A

∆S = S(final) - S(initial)

20
Q

What is entropy a measure of

A

A measurement of disorder

21
Q

What is important at ∆G=0

A

At ∆G=0, we can use this value to work out the temp the reaction becomes feasible

22
Q

When you have a -enthalpy and a +entropy, will this be feasible

A

Always feasible

23
Q

When you have a -enthalpy and a -entropy, will this be feasible

A

Feasible at low temps

24
Q

When you have a +enthalpy and a -entropy, will this be feasible

A

Never feasible

25
Q

When you have a +enthalpy and a +entropy, will this be feasible

A

Only at high temps

26
Q

How does ΔG = ΔH - ΔST work with a straight line graph

A

ΔG = -ΔS T + ΔH
Y = M X + C