Entropy

Question 1

Entropy

Answer 1

A measure of randomness or disorder

Question 2

Three factors that cause change in entropy

Answer 2

Change of state
Dissolving solid ionic lattice
Change in number of moles

Question 3

Change in state influence on entropy

Answer 3

Gases have more energy than liquid because the particles are available to move randomly
Gas>liquid>solid

Question 4

Influence of dissolving a solid ionic lattice on entropy

Answer 4

When a solid dissolved ions become separated and hydrated
This increases entropy

Question 5

Change in number of moles influence in entropy

Answer 5

More moles of products than reactants increases entropy

Question 6

ΔSsys

Answer 6

The entropy change in the system
(Reactants and products)
Σproducts - Σreactants

Question 7

ΔSsurr

Answer 7

The entropy change in surroundings

Question 8

ΔStot

Answer 8

ΔSsys + ΔSsurr

Question 9

change in entropy in this reaction:
NH3 (g) + HCl (g)-> NH4Cl (s)

Answer 9

decrease due to change in state

Question 10

Change in state on this reaction:
NH4NO3 (s) → NH4+ (aq) + NO3– (aq)

Answer 10

Increase due to dissolving solid

Question 11

Change in entropy in this reaction:
2CH3COOH + (NH4)2CO3 → 2CH3COONH4 + H2O + CO2

Answer 11

Increase because increase in moles and gas release

Question 12

Change in entropy in this reaction:
2Mg + O2 -> 2MgO2

Answer 12

Decrease in entropy
Gas to solid
Decrease in moles

Question 13

Entropy change of surroundings equation

Answer 13

Δ Surroundings= - ΔH/T

Question 14

ΔG

Answer 14

ΔG=ΔH-TΔSsystem

Question 15

Lattice energy definition

Answer 15

Energy change when 1 mole of ionic solid is formed from its ions in gaseous state

Question 16

ΔHlatt
Lattice enthalpy

Answer 16

Measure of the strength of attractive forces in an ionic compound

Question 17

If ΔS total is positive what does this show about the reaction

Answer 17

Feasible/spontaneous at 298K

Question 18

If energy is released into the surroundings, what will happen to ΔSsurr

Answer 18

ΔS surr will increase

Question 19

Calculating ΔH from formation data

Answer 19

ΔH = ΔHf products - reactants
PROOF
Units: Jmol-1K-1

Question 20

Spontaneous meaning

Answer 20

(Reaction will continue to occur without further input)
Exam answer: a reaction where ΔS total is positive of ΔG is negative

Question 21

ΔG formula

Answer 21

ΔG=ΔH-TΔSsys
T in Kelvin
Jmol-1K-1

Question 22

On to calculate temperature at which reaction is spontaneous

Answer 22

T= ΔH/ΔSsystem

Question 23

Reason for large disparity between theoretical and experimental lattice energy