Chem 101B Chapter 15: Solution Equilibria Practice Test

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Questions and Answers

Predict whether adding potassium nitrate impacts the solubility of ammonium nitrate. NH4NO3(s) ⇌ NH4+ (aq) + NO3-(aq)

Solubility does not change

Solubility decreases (correct)

Solubility increases

The correct mathematical expression for finding the molar solubility (S) of Sn(OH)2 is:

8S3 = Ksp

2S3 = Ksp

4S3 = Ksp

2S2 = Ksp (correct)

108S5 = Ksp

The molar solubility of AgCl (Ksp = 1.6 × 10⁻¹⁰) in 0.0034 M sodium chloride at 25°C is:

1.6 × 10⁻¹⁰

5.4 × 10⁻¹³

4.7 × 10⁻⁸ (correct)

0.0034

none of these

Which of the following processes is spontaneous under the specified conditions?

CO2(s) → CO2(g) at 0°C Signup and view all the answers

A certain process has ΔSuniv > 0 at 25°C. What does one know about the process?

It is spontaneous at 25°C. Signup and view all the answers

Which of the following is always true for an exothermic process?

q sys < 0, ΔSsurr > 0 Signup and view all the answers

For a reaction in a voltaic cell, both ΔH° and ΔS° are positive. Which of the following statements is true?

E°cell will increase with an increase in temperature. Signup and view all the answers

The heat of vaporization for 1.0 mole of water at 100°C and 1.0 atm is 40.56 kJ/mol. Calculate ΔS for the process H2O(l) → H2O(g) at 100°C.

406 J/K mol Signup and view all the answers

The standard free energy of formation of AgI(s) is –66.2 kJ/mol. What is ΔG° for the reaction 2AgI(s) → 2Ag(s) + I2(s)?

–132.4 kJ Signup and view all the answers

Given: CH3COOH(aq) ⇌ H+(aq) + CH3COO–(aq) Ka = 1.75 × 10⁻⁵ at 25°C. What is ΔG at 25°C for the solution?

–19.7 kJ Signup and view all the answers

Select all that apply. Place a check for all processes that involve an increase in the entropy of the system.

Heating 1.0 mol of an ideal gas at constant volume Signup and view all the answers

For each pair, which species has the higher entropy? Write it in the space provided, followed by explain why it is higher. a. Mg(NO₃)₂(s), Mg(NO₃)₂(aq)

Mg(NO₃)₂(aq) Signup and view all the answers

What is the oxidation state for the nitrogen atom in HNO3?

5 Signup and view all the answers

What is the oxidation state for the nitrogen atom in NO2?

4 Signup and view all the answers

What is the oxidation state for the nitrogen atom in N2O?

1 Signup and view all the answers

What is the oxidation state for nitrogen in NH4Cl?

-3 Signup and view all the answers

What is the oxidation state for nitrogen in NaNO2?

+3 Signup and view all the answers

In the reaction 2Ca(s) + O2(g) → 2CaO(s), which species is oxidized?

Ca Signup and view all the answers

In the reaction 2Cs(s) + Cl2(g) → 2CsCl(s), Cl2 is:

the oxidizing agent. Signup and view all the answers

In the reaction N2(g) + 3H2(g) → 2NH3(g), N2 is:

reduced. Signup and view all the answers

Given the reaction: 2MnO4– + 5H2O2 + 6H+ → 2Mn2+ + 8H2O + 5O2, determine the number of electrons involved in this reaction.

10 Signup and view all the answers

Which of the following are oxidation-reduction reactions? I. PCl3 + Cl2 → PCl5 II. Cu + 2AgNO3 → Cu(NO3)2 + 2Ag III. CO2 + 2LiOH → Li2CO3 + H2O IV. FeCl2 + 2NaOH → Fe(OH)2 + 2NaCl

I and II Signup and view all the answers

Study Notes

Constants

R = 8.3145 J/(K·mol)
R = 0.08206 L·atm/(K·mol)

Equations

ΔSsurr = –ΔH/T
ΔG = ΔH - TΔS
ΔG° = -RT lnK
ΔG° = ΔH° - TΔS°
ΔG = ΔG° + RT lnQ

Solution Equilibria

Effects of adding a common ion on solubility:
- Adding potassium nitrate to a solution of ammonium nitrate may affect its solubility
Molar solubility (S) of Sn(OH)2:
- Expression: 2S2 = Ksp
Factors affecting solubility:
- Presence of common ions
- Concentration of ions

Thermochemistry

Spontaneity of processes:
- ΔSsurr > 0 indicates a spontaneous process
Exothermic and endothermic processes:
- Exothermic: ΔSsurr < 0, q sys < 0
- Endothermic: ΔSsurr > 0, q sys > 0
Relation between ΔG° and E°cell:
- E°cell will increase with an increase in temperature if ΔS° is positive
Standard free energy of formation (ΔG°f):
- Example: ΔG°f for AgI(s) is -66.2 kJ/mol

Thermodynamics

Entropy (S):
- Increases with increase in disorder or randomness
- Example: mixing 5 mL ethanol with 25 mL water increases entropy
Thermodynamic parameters:
- ΔSsystem: positive for increase in entropy
- ΔHsystem: positive for endothermic, negative for exothermic
- ΔSsurrounding: opposite of ΔSsystem
- ΔG: negative for spontaneous, positive for non-spontaneous
- ΔSuniverse: always increases

Electrochemistry

Oxidation and reduction:
- Oxidation: loss of electrons
- Reduction: gain of electrons
Examples of oxidation-reduction reactions:
- 2Ca(s) + O2(g) → 2CaO(s)
- 2Cs(s) + Cl2(g) → 2CsCl(s)
Identifying oxidizing and reducing agents:
- Oxidizing agent: O2 in 2Ca(s) + O2(g) → 2CaO(s)
- Reducing agent: Ca in 2Ca(s) + O2(g) → 2CaO(s)

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Description

Practice quiz for Chem 101B Chapter 15, covering solution equilibria and related equations and constants. Test your knowledge on thermodynamic properties and chemical reactions.