Entropy

Question 1

Entropy is to do with the?

Answer 1

arrangement and movement of particles

Question 2

Enthalpy?

Answer 2

the energy involved in chemical bonds

Question 3

Entropy is made of?

Answer 3

• made up of vibrational, rotational and translational energies (to do w movement)

Question 4

Entropy is measured as?

Answer 4

• measured as the amount of extra energy of motion (in Joules) that is added per mole of a substance for each degree K the temp rises

Question 5

Entropy symbol?

Answer 5

• S, standard entropy = S^theta

Question 6

units for entropy?

Answer 6

JK-1mol-1/ JoulesK-1mol-1

Question 7

why do metals have a higher entropy than ionic lattice?

Answer 7

metal = delocalised e-s able to move which creates disorder

Question 8

solids have ? entropy

Answer 8

low - only vibrational energy

Question 9

gases have ? entropy

Answer 9

high, disordered particles free to move around

Question 10

why does H2O have a more regular structure?

Answer 10

H bonds

Question 11

What are the 2 factors that can cause an increase in entropy?

Answer 11

changing state and increasing the number of moles

Question 12

Why does salt dissolve in water?

Answer 12

• solid is more ordered = low entropy, entropy increases as solid turns into liquid

Question 13

entropy is all about

Answer 13

disorder

Question 14

change in entropy=

Answer 14

total of entropy of products - total entropy of reactants

Question 15

negative entropy means?

Answer 15

amount of disorder has decreased, entropy has decreased

Question 16

increasing no. of moles =

Answer 16

increased disorder

Question 17

in entropy calc take into account

Answer 17

no. of moles

Question 18

entropy & energy?

Answer 18

Less KE = lower entropy

Question 19

what would happen to entropy at OK?

Answer 19

• Movement of particles stops

* could still be disorder due to arrangement so entropy would be around 0

Question 20

Change in entropy symbol?

Answer 20

ΔS

Question 21

What kind of entropy change is favourable?

Answer 21

POSITIVE - more likely to occur

Question 22

⭐ Entropy definition

Answer 22

The energy of a substance, contained as a result of the movement of particles and arrangement.

Question 23

⭐ Enthalpy definiton?

Answer 23

the energy of a substance, contained within bonds/ forces

Question 24

Which reaction is favourable in terms of H?

Answer 24

• exo
• products have lower enthalpy level and, exo reactions have a smaller Ea
• so products = less reactive, more stable than products of endo

Question 25

What does free energy change do?

Answer 25

• ΔG
• determines whether or not a reacion is feasible by considering ΔS and ΔH
• feasible reaction = one that is likely to take place
• but no indication of how fast a reaction will occur

Question 26

ΔGθ =

Answer 26

ΔHθ - TΔSθ

Question 27

ΔGθ & ΔHθ, ΔS units units in the equation?

Answer 27

kJmol-1

Divide ΔS value by 1000 to get kJk-1mol-1

Question 28

T units?

Answer 28

K - degrees + 273

Question 29

θ means T =

Answer 29

298K

Question 30

if ΔG = -

Answer 30

the reaction is feasible

Question 31

if ΔG = +,

Answer 31

reaction is not feasible

Question 32

if ΔG = 0

Answer 32

we can rearrange to find the T at which the reaction becomes feasible

Question 33

T =

Answer 33

ΔH/ ΔS

Question 34

For ΔH?

Answer 34

Draw Hess’ cycle

Question 35

in order to get a minus delta G value?

Answer 35

TΔS > ΔH