Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

OCR A level Chemistry > Lattice enthalpy > Flashcards

Lattice enthalpy Flashcards

1
Q

Define lattice enthalpy

A

The enthalpy change associated with the formation of one mole of an IONIC compound from its gaseous ions under standard conditions

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

What is the symbol for lattice enthalpy

A

ΔLeHϴ

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

What symbol accompanies lattice enthalpy?

A

-

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

Why is lattice enthalpy always negative?

A

It represents the formation of bonds which releases energy and so is exothermic

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

Write an equation to represent the lattice enthalpy of NaCL

A

Na+ (g) + Cl- (g) —-> NaCl(s)

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

What is the definition of enthalpy of formation?

A

The enthalpy change that accompanies the formation of one mole of a substance from its elements under standard conditions with 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 definition of 1st ionisation energy?

A

The amount of energy required to remove one electron from each atom in one mole of gaseous atoms OF AN ELEMENT to form one mole of gaseous 1+ ions

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

Write an equation for 1st ionisation energy

A

Na(g) —–> Na+ (g) + e-

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

What is the sign of ionisation energy?

A

+

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

Why is ionisation always positive?

A

Energy is required to pull the electron being removed away from the nucleus

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

As more electrons are removed what happens to the value of IE and why?

A

The value increases
As more electrons are removed the remaining electrons are pulled in closer to the nucleus and so more energy is required to remove the electrons

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

What is the definition of enthalpy of atomisation?

A

The enthalpy change that takes place for 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
13
Q

What is the sign for enthalpy of atomisation?

A

Always +

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

Why is the sign of enthaply of atomisation always +?

A

Bonds holding atoms together in their standard states must be broken

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

What is the definition of 1st electron affinity?

A

Th energy change that accompanies the addition of one electron to each atom in one mole of atoms of an element on gaseous form to form one mole of gaseous 1- ions

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

Is 1st Electron affinity exothermic?

A

Yes

17
Q

Why is 1st electron affinity exothermic?

A

An electron is being added and will be attracted to the nucleus

18
Q

Are subsequent electron affinities exothermic?

A

No

19
Q

Why are subsequent electron affinities endothermic?

A

Electrons are being added to a negatively charged ion, and it is necessary to overcome the repulsion

20
Q

From the bottom left hand side round to the bottom right hand side, what is the order of enthalpy changes?

A
  • Formation
  • Atomisation
  • 1st ionisation energy
  • any subsequent ionisation energies
  • atomisation
  • 1st electron affinity
  • any subsequent electron affinities
  • lattice enthalpy
21
Q

Define enthalpy of hydration

A

The enthalpy change when one mole of isolated gaseous ions is dissolved in water under standard conditions

22
Q

Define enthalpy change of solution

A

The enthalpy change when one mole of a substance is completely dissolved in water under standard conditions

23
Q

What is the symbol for enthalpy change of solution?

A

ΔsolHϴ

24
Q

What is the symbol for enthalpy change of hydration?

A

ΔhydHϴ

25
Q

Is the enthalpy change of solution endothermic or exothermic?

A

Either

26
Q

Is the enthalpy change of hydration endothermic or exothermic?

A

Exothermic

27
Q

Why is the enthalpy change of hydration exothermic?

A

Bonds are being formed between ions and water

28
Q

Are the lattice enthalpies of larger ions more or less exothermic?

A

Less

29
Q

Why do larger ions have a less exothermic lattice enthalpy?

A
  • the electrostatic attraction between the ions is weaker

- because the ions have a lower charge density

30
Q

How is charge density calculated?

A

charge/volume

31
Q

Are the lattice enthalpies of more highly charge ions more or less exothermic?

A

More

32
Q

Why do more highly charged ions have a more exothermic lattice enthalpy?

A
  • the electrostatic attraction between the ions is stronger

- because the charge density is higher

33
Q

Do smaller ions have a more or less exothermic value of enthalpy of hydration?

A

More

34
Q

Why do smaller ions have a more exothermic enthalpy of hydration?

A
  • smaller ions have larger charge densities

- so attract water molecules more strongly

35
Q

Do ions with a smaller charge have more or less exothermic enthalpies of hydration?

A

Less

36
Q

Why do ions with a smaller charge have a less exothermic enthalpy of hydration?

A
  • the ions have smaller charge densities

- so they cannot attract water molecules as strongly

OCR A level Chemistry (30 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions