Unit 8 - Kinetics & Equilibrium - Honors

Question 1

What is ΔS? (3)

Answer 1

1. Symbol for Change in Entropy
2. S itself can never be negative (nothing can be less random than 0)
3. Units: J/molK

Question 2

What is the formula for ΔS? (3)

Answer 2

1. S (final) - S (initial)
2. -ΔS = Decrease in Entropy (less random)
3. +ΔS = Increase in Entropy (more random)

Question 3

Definition of Standard Molar Entropies (3)

Answer 3

1. Scale relative to H+ (aq)
2. H+(aq) S° = 0
3. Ex: F has 13.8 units less than H+ = -13.8J/molK

Question 4

What is the trend relating to ΔS and molar mass & temp? (4)

Answer 4

1. Entropy increases when molar mass increases
2. As molecule increases in complexity, there’s more ways to be random
3. Entropy increases when temperature increases
4. As molecule movement speeds up, there will be more disorder

Question 5

Definition of Keq (2)

Answer 5

1. Equilibrium constant
2. Ratio of Conc. of Products & Reactant at equilibrium

Question 6

How do you calculate Keq? (5)

Answer 6

1. Keq = Products/Reactants
2. Convert coefficients in chemical equation
3. To exponents in mathematical equation
4. ALWAYS MULTIPLY, DO NOT ADD
5. (s) & (l) in a chemical equation cannot concentrate, so ~1

Question 7

What does it mean when the value of Keq is big or small? (2/2/1)

Answer 7

Keq is big
1. More Product than Reactant
2. Rxn favors production of products in forward rxn
Keq is small
1. Less Product than Reactant
2. Rxn favors production of reactants in reverse rxn
Keq is ~1
1. About same amount of Product & Reactant

Question 8

What is something to keep in mind about Solids & Liquids in a Chemical Formula when Calculating Keq

Answer 8

Solids and Liquids cannot Concentrate, so it is equivalent to 1.