5.2.2 - Enthalpy and entropy

Question 1

Entropy

Answer 1

Measure of the dispersal of energy in a system

Question 2

When is entropy higher

Answer 2

The more disordered or random something is

Question 3

Why do gases have the most entropy

Answer 3

Particles are moving rapidly and randomly

S (gas)&raquo_space; S (liquid) > S (solid)

Question 4

2nd law of thermodynamics

Answer 4

Entropy naturally increases over time

Cannot decrease

Question 5

3rd law of thermodynamics

Answer 5

Entropy of a substance is zero at absolute zero (0K) as it has a perfect order

Question 6

The higher the temperature ..

Answer 6

The faster the particles vibrate/move and so the greater the entropy (disorder )

Question 7

Where are the biggest increases in entropy

Answer 7

State changes (melting and boiling)
Esp boiling due to a large amount of disorder in gases compared to solids and liquids

Question 8

Why does water have a low entropy

Answer 8

H bonds - spp bond angle (180)

Question 9

When does entropy decrease

Answer 9

When you go from disorder to order

Question 10

Calculating entropy change

Answer 10

Sum S products - Sum S reactants

S is +ve - increase in entropy
S is -ve - Decrease in entropy

Question 11

Gibbs free energy change

Answer 11

G = delta formation - T (S)

T in Kelvin
H/S in joules per mole
G in kJ/mol

Question 12

When is a reaction feasible

Answer 12

If G is less than or equal to 0

Question 13

Why may a feasible reaction not actually take place

Answer 13

High activation energy

Question 14

Spontaneous processes

Answer 14

Physical or chemical processes that occur w/out outside intervention

Question 15

Predicting general change of entropy

Answer 15

X moles of s/l/g forms X moles of s/l/g

… has higher/lower disorder and the entropy of the p/r is higher /lower than the r/p