x Flashcards

1
Q

lattice enthalpy definition

A

measure of the strength of ionic bonding in a giant ionic lattice

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

what is the purpose of Born- Haber cycles

A

determines the lattice enthalpy indirectly

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

what sort of energy change is needed to form gaseous atoms? why?

A
  • endothermic

- involves breaking bonds

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

what sort of energy change is needed to form gaseous ions?

A

endothermic

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

what sort of energy change is needed to form a lattice

A

exothermic

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

standard enthalpy change of formation definition

A

formation of 1 mol of a compound from its elements in its standard states under standard conditions

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

standard enthalpy change of atomisation definition

A

formation of one mole of gaseous atoms from the element in its standard states under standard conditions

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

first electron affinity definition

A

addition of 1 mol of electrons to 1 mol of gaseous atoms to form 1 mol of gaseous 1- ions

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

enthalpy change of hydration definition

A

dissolving of 1 mol of gaseous ions in water

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

explain why the 2nd ionisation is more endothermic than the 1st ionisation

A
  • Mg+ has one more proton than electrons
  • increase nuclear attraction
  • decrease radius
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what energy is needed in the second electron affinity

A

enothermic

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

what energy is needed in the second electron affinity

A

endothermic

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

write the equation to calculate energy change

A

q=mc∆T

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

what 2 processes take place when ionic compounds dissolve in water

A
  • ionic lattice breaks up

- water molecules are attracted to, and surround, the ions

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

what are the general properties of ionic compounds?

A
  • high melting and boiling points
  • soluble in polar solvents
  • conduct electricity when molten or in aqueous solution
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

effect of ionic size on lattice enthalpy

A
  • ionic radius increases
  • attraction between ions decrease
  • lattice enthalpy less negative
  • melting point decreases
17
Q

effect of ionic charge on lattice enthalpy

A
  • ionic charge increases
  • attraction between ions increase
  • lattice energy becomes more negative
  • melting point increases
18
Q

effect of ionic charge size from left to right

A
  • increasing charge gives more attraction

- decreasing size gives more attraction

19
Q

effect of ionic charge size from right to left

A
  • increasing charge gives more attraction

- increasing size gives less attraction

20
Q

effect of ionic size on hydration enthalpy down group 1

A
  • ionic radius increases
  • attraction between ion and water molecules decreases
  • hydration energy less negative
21
Q

effect of ionic size on hydration enthalpy down group 1

A
  • ionic radius increases
  • attraction between ion and water molecules decreases
  • hydration energy less negative
22
Q

effect of ionic charge on hydration enthalpy

A
  • ionic charge increases
  • attraction with water molecules increases
  • hydration energy become more negative
23
Q

what can entropy be used to predict

A
  • a gas spreading through a room
  • heat from a fire spreading through a room
  • ice melting in a hot room
24
Q

general rules of entropy

A
  • solids have the smallest entropies
  • liquids have greater entropies
  • gases have the greatest entropies
25
what will the entropy change be if a system changes to become more random
- energy becomes more spread out | - ∆S is positive
26
what will the entropy change be if a system changes to become less random
- energy becomes more concentrated | - ∆S is negative
27
when any substance changes state from solid to liquid to gas, its entropy increases:
- melting and boiling increase the randomness of particles | - energy is spread out more and ∆S is positive
28
describe the entropy of this reaction: | N₂(g) +3H₂(g) -> 2NH₃(g)
- decrease in the randomness of particles | - energy is spread out less and ∆S is negative
29
standard entropy of a substance
entropy of 1 mole of a substance, under standard conditions (100kPa and 298K)
30
standard enthalpy facts
- JK⁻¹mol⁻¹ | - always positive
31
calculate entropy changes
∆S=ΣS(products)-ΣS(reactants)
32
calculate entropy changes
∆S=ΣS(products)-ΣS(reactants)
33
write the Gibb's equation
∆G=∆H-T∆S
34
enthalpy change, ∆H
heat transfer between the chemical system and the surroundings
35
entropy change at the temperature of the reaction, T∆S
dispersal of energy within the chemical system itself
36
conditions for feasibility
- ∆G<0
37
limitations of predictions made for feasibility
rate of reaction is very slow