EXTRA HOMEWORK 3A - Saddleback College · EXTRA HOMEWORK 3A 1. ... The standard enthalpy change of...

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EXTRA HOMEWORK 3A 1. Calculate the standard enthalpy change, ΔHº, for the reaction: 2H 2 O 2 (l) 2H 2 O (l) + O 2 (g) (a) using the standard enthalpy of formations from Handout 5 (b) using bond energies from the Chem 1A Handout 8 2. In each of the following pairs, tell which has the higher entropy. (a) One mole of ice or one mole of liquid water (b) One mole of liquid propane or one mole of gaseous propane (c) One mole of tin or one mole of lead (d) One mole of solid magnesium nitrate or one mole of aqueous magnesium nitrate 3. Will the entropy change of each of the following processes be positive or negative, and will the disorder in each process increase or decrease? (a) One mole of solid aluminum melting to one mole of molten aluminum. (b) One mole of iodine vapor deposing to one mole of solid iodine (c) One mole of dissolved sodium acetate crystallizing out of an aqueous solution (d) One mole of dissolved carbon dioxide bubbling out of a soda 4. Predict the sign of the entropy change in each of the following reactions. (a) BaCO 3 (s) BaO (s) + CO 2 (g) (b) Mg (s) + Cl 2 (g) MgCl 2 (s) (c) CH 4 (g) + 2O 2 (g) 2CO 2 (g) + 2H 2 O (l) (d) Ni 3 (PO 4 ) 2 (s) 3Ni 2+ (aq) + 2PO 4 3- (aq) (e) 2H + (aq) + SO 3 2- (aq) H 2 O (l) + SO 2 (g) (f) Br 2 (l) + Cl 2 (g) 2BrCl (l) 5. Using the data from Handout 5, what is the standard enthalpy of formation of N 2 O (g)? What does this mean? 6. Using the data from Handout 5, what is the standard absolute entropy of N 2 O (g)? What does this mean? 7. Using data from the appendix, calculate the standard change in entropy, ΔSº, for the following reactions. (a) 2S (s, monoclinic) + 3O 2 (g) 2SO 3 (g) (b) C 3 H 8 (g) + 5O 2 (g) 3CO 2 (g) + 4H 2 O (g) (continued on next page)

Transcript of EXTRA HOMEWORK 3A - Saddleback College · EXTRA HOMEWORK 3A 1. ... The standard enthalpy change of...

Page 1: EXTRA HOMEWORK 3A - Saddleback College · EXTRA HOMEWORK 3A 1. ... The standard enthalpy change of combustion for butyric acid at 298 K is -2,184 ... -ion in a 1.00 M solution of

EXTRA HOMEWORK 3A

1. Calculate the standard enthalpy change, ΔHº, for the reaction:

2H2O2 (l) 2H2O (l) + O2 (g)

(a) using the standard enthalpy of formations from Handout 5

(b) using bond energies from the Chem 1A Handout 8

2. In each of the following pairs, tell which has the higher entropy.

(a) One mole of ice or one mole of liquid water

(b) One mole of liquid propane or one mole of gaseous propane

(c) One mole of tin or one mole of lead

(d) One mole of solid magnesium nitrate or one mole of aqueous magnesium nitrate

3. Will the entropy change of each of the following processes be positive or negative, and will the

disorder in each process increase or decrease?

(a) One mole of solid aluminum melting to one mole of molten aluminum.

(b) One mole of iodine vapor deposing to one mole of solid iodine

(c) One mole of dissolved sodium acetate crystallizing out of an aqueous solution

(d) One mole of dissolved carbon dioxide bubbling out of a soda

4. Predict the sign of the entropy change in each of the following reactions.

(a) BaCO3 (s) → BaO (s) + CO2 (g)

(b) Mg (s) + Cl2 (g) → MgCl2 (s)

(c) CH4 (g) + 2O2 (g) → 2CO2 (g) + 2H2O (l)

(d) Ni3(PO4)2 (s) → 3Ni2+

(aq) + 2PO43-

(aq)

(e) 2H+

(aq) + SO32-

(aq) H2O (l) + SO2 (g)

(f) Br2 (l) + Cl2 (g) → 2BrCl (l)

5. Using the data from Handout 5, what is the standard enthalpy of formation of N2O (g)? What does this

mean?

6. Using the data from Handout 5, what is the standard absolute entropy of N2O (g)? What does this

mean?

7. Using data from the appendix, calculate the standard change in entropy, ΔSº, for the following

reactions.

(a) 2S (s, monoclinic) + 3O2 (g) → 2SO3 (g)

(b) C3H8 (g) + 5O2 (g) 3CO2 (g) + 4H2O (g)

(continued on next page)

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*8. 4 molecules are placed in a two-bulbed container. Calculate the positional probability of finding all 4

molecules in the left bulb.

*9. 8 molecules are placed in a two-bulbed container. Calculate the positional probability of finding all 8

molecules in the left bulb.

EXTRA HOMEWORK 3B

1. Predict whether each of the following processes will be spontaneous, nonspontaneous, or it cannot be

determined.

(a) ∆H = + and ∆S = +

(b) ∆H = + and ∆S = –

(c) ∆H = – and ∆S = +

(d) ∆H = – and ∆S = –

2. Using the data from Handout 5, what is the standard free energy of formation of N2O (g)? What does

this mean?

3. For the reaction at 298 K

Fe2O3 (s) + 3H2 (g) 2Fe (s) + 3H2O (g)

use data from Handout 5 to answer the following.

(a) Calculate ΔHº

(b) Calculate ΔSº

(c) Calculate ΔGº

(d) Calculate ΔGº from ΔGº = ΔHº - T ΔSº

(e) Is the reaction spontaneous under standard conditions at 298 K?

(f) Do the enthalpy change and the entropy change work for or against spontaneity?

(g) At a temperature higher than 298 K, would the forward reaction be more or less spontaneous?

4. For the reaction at 298 K

3AuCl (s) 2Au (s) + AuCl3 (s)

use the data below to answer the following.

298

ΔHºf (kJ/mol) 298

ΔGºf (kJ/mol) 298

Sº (J/molK)

AuCl (s) -97 -105 91

AuCl3 (s) -118 -127 157

(a) Calculate ΔHº, ΔGº, and ΔSº for the reaction at 298 K.

(b) Calculate the absolute entropy of elemental gold at 298 K.

(c) What is ΔHº, ΔSº, and ΔGº for the reaction at 398 K?

(continued on next page)

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5. For the phase change:

C6H6 (l) C6H6 (g)

∆Hº = 33.9 kJ and ∆Sº = 96.4 J/K.

(a) Calculate the standard free energy change, ΔGº, for the reaction at 293 K, and tell if the forward

or reverse reaction is spontaneous at this temperature

(b) Calculate the standard free energy change, ΔGº, for the reaction at 353 K, and tell if the forward

or reverse reaction is spontaneous at this temperature

(c) Calculate the boiling point of liquid benzene

*6. For the phase change:

I2 (s) I2 (g)

ΔHº = 62.24 kJ/mol and ΔSº = 143.6 J/molK.

(a) Calculate the standard free energy change, ΔGº, for the reaction at 100.ºC, and tell if the forward

or reverse reaction is spontaneous at this temperature.

(b) Calculate the standard free energy change, ΔGº, for the reaction at 200.ºC, and tell if the forward

or reverse reaction is spontaneous at this temperature.

(c) Calculate the sublimation point of solid iodine.

*7. The combustion reaction for butyric acid is:

C3H7CO2H (l) + 5O2 (g) → 4H2O (l) + 4CO2 (g)

The standard enthalpy change of combustion for butyric acid at 298 K is -2,184 kJ/mol, and the

standard entropy change of combustion for butyric acid at 298 K is -117 J/molK .

ΔHºf (kJ/mol) Sº (J/molK)

C (s) 0 +6

CO2 (g) -394 +214

H2 (g) 0 +131

H2O (l) -286 +70.

O2 (g) 0 +205

C3H7CO2H (l) ? +226

(a) Calculate the standard enthalpy change of formation, ΔHºf, for butyric acid at 298 K.

(b) Write the correctly balanced equation for the formation of butyric acid from its elements.

(c) Calculate the standard entropy change of formation, ΔSºf, for butyric acid at 298 K.

(d) Calculate the standard free energy change of formation, ΔGºf, for butyric acid at 298 K.

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EXTRA HOMEWORK 3C

1. For the reaction:

2NO2 (g) ⇆ N2O4 (g)

use data from Handout 5 to answer the following.

(a) Calculate ΔGº at 298 K

(b) If the pressures of the gases are pNO2 = 0.29 atm and pN2O4 = 1.6 atm, calculate ΔG at 298 K, and

predict the direction the reaction will shift to reach equilibrium.

(c) If the pressures of the gases are pNO2 = 0.21 atm and pN2O4 = 0.50 atm, calculate ΔG at 298 K, and

predict the direction the reaction will shift to reach equilibrium.

(d) If the pressures of the gases are pNO2 = 1.0 atm and pN2O4 = 1.0 atm, calculate ΔG at 298 K, and

predict the direction the reaction will shift to reach equilibrium.

2. For the reaction

3H2 (g) + N2 (g) ⇆ 2NH3 (g)

use data from Handout 5 to answer the following.

(a) Calculate ΔGº at 298 K

(b) Is the forward reaction spontaneous under standard conditions?

(c) Predict whether the equilibrium constant be > 1 or < 1 at 298 K.

(d) Calculate Keq at 298 K

(e) Does the Keq favor reactants or products?

(f) What effect would an increase in pressure have on the spontaneity of the reaction?

3. For the combustion of liquid methanol:

C2H5OH (l) + 3O2 (g) → 2CO2 (g) + 3H2O (l)

(a) Calculate ΔGº at 298 K

(b) Is the reaction spontaneous under standard conditions?

(c) Predict whether the equilibrium constant be > 1 or < 1 at 298 K

(d) Calculate Keq at 298 K

(e) Does the Keq favor reactants or products?

(f) What effect would an increase in temperature have on the spontaneity of the reaction?

(g) What effect would an increase in pressure have on the spontaneity of the reaction?

(continued on next page)

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4. Nitrous acid ionizes according to the following equation:

HNO2 (aq) ⇆ H+

(aq) + NO2- (aq)

At 298 K the ΔG°f for nitrous acid is -51.6 kJ/mol, and the ΔG°f for the nitrite ion is -32.2 kJ/mol.

(a) Calculate the standard free energy change of the reaction at 298 K.

(b) Is the reaction spontaneous under standard conditions?

(c) Predict whether the Ka of nitrous acid will be > 1 or < 1 at 298 K.

(d) From the standard free energy change of the reaction, calculate the Ka of acetic acid at 298 K.

(e) How does your calculated Ka compare with the value found on Handout 3?

(f) If the concentrations of each species in solution are [HNO2] = 0.100M, [H+] = 1.00 x 10

-3 M, and

[NO2-] = 1.00 x 10

-3 M, calculate ΔG at 298 K.

(g) Is the reaction spontaneous under the conditions in (f)?

5. Benzoic acid (C6H5CO2H) is a weak organic acid with Ka = 6.5 x 10-5

at 298 K.

(a) Write the equilibrium constant expression for the ionization of benzoic acid in water.

(b) What is molarity of the benzoate ion, C6H5CO2- ion in a 1.00 M solution of benzoic acid in water?

(c) What is the pH of the solution?

(d) Predict whether ΔG° for the reaction in (a) will be > 0 or < 0 at 298 K.

(e) What is the standard free energy change of the ionization of benzoic acid in water?

6. The solubility of tin (II) fluoride in water is 0.049 g/L at 20.ºC and 0.093 g/L at 80.°C.

(a) Calculate the Ksp for tin (II) fluoride at each temperature.

(b) Determine the heat of solution and the entropy change of solution of tin (II) fluoride by using a

van’t Hoff plot.

(continued on next page)

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*7. Hydrazine is a weak base that dissociates in water according to:

N2H4 (aq) + H2O (l) ⇆ N2H5+

(aq) + OH- (aq)

The Kb for hydrazine at 298 K is 2.4 x 10-6

. and aqueous hydrazine has a standard free energy of

formation of 128 kJ/mol. Calculate the standard free energy of formation of the hydrazinium ion.

*8. The tables below contain information for determining thermodynamic properties of the following

reaction:

C2H5Cl (g) + Cl2 (g) → C2H4Cl2 (g) + HCl (g)

ΔGºf (kJ/mol) at 298 K

C2H5Cl (g) -61

Cl2 (g) 0

C2H4Cl2 (g) -80.

HCl (g) -95

Bond Bond Energy (kJ/mol) at 298 K

C-H 414

C-C 347

C-Cl 377

Cl-Cl 243

H-Cl 431

(a) Calculate the ΔGº for the reaction above, using the table of standard free energy changes of

formation.

(b) Calculate the ΔHº for the reaction above, using the table of bond energies.

(c) Calculate the ΔSº for the reaction above at 298 K.

(d) Calculate the equilibrium constant for the reaction at 298 K.

(e) What is the effect of an increase in temperature on the value of the equilibrium constant?

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EXTRA HOMEWORK 3D

1. Assuming the concentrations of 1 M for all of the following solutions, use standard reduction potentials

found in Table 18.1 to determine which of the following reactions are spontaneous.

(a) Ba (s) + Fe2+

(aq) → Ba2+

(aq) + Fe (s)

(b) 2Au (s) + 3Br2 (l) → 2Au3+

(aq) + 6Br- (aq)

(c) H2SO3 (aq) + H2O (l) + Pb2+

(aq) → SO42-

(aq) + 4H+

(aq) + Pb (s)

(d) Cd (s) + 2H+

(aq) → Cd2+

(aq) + H2 (g)

2. Consider a standard cell composed of a Zn | Zn2+

(1 M) half-cell and a Sn | Sn2+

(1 M) half-cell

(a) Determine the spontaneous chemical reaction that takes place in this cell, assuming that the line

notation may be written incorrectly

(b) What is Ɛº for the cell?

(c) Which metal, Zn or Sn, will be the anode, and which metal will be the cathode?

(d) Do the electrons flow from Zn to Sn in the external circuit, or the other way?

(e) What is the shorthand line notation for this cell?

3. Consider a standard cell composed of a Ba | Ba2+

(1 M) half-cell and a Cr | Cr3+

(1 M) half-cell

(a) Write the spontaneous chemical reaction that takes place in this cell

(b) What is Ɛº for the cell?

(c) Which metal, Ba or Cr, will be the cathode, and which metal will be the anode?

(d) Do the electrons flow from Ba to Cr in the external circuit, or the other way?

(e) What is the shorthand line notation for this cell?

4. Find the missing standard reduction potentials for these following half reactions on Handout 5:

MnO2 (s) + 4H+ (aq) + 2e

- → Mn

2+ (aq) + 2H2O (l) Ɛ ° = +1.21 V

Ag+ (aq) + e

- → Ag (s) Ɛ ° = +0.80 V

I2 (s) + 2e- → 2I

- (aq) Ɛ ° =

PbSO4 (s) + 2e- → Pb (s) + SO4

2- (aq) Ɛ ° =

2H+ (aq) + VO2

+ (aq) + e- → VO

2+ (aq) + H2O (l) Ɛ ° =

Assuming all reactants and products are at unit activity,

(a) What substance from above is the best oxidizing agent and what is the best reducing agent?

(b) Will manganese (IV) oxide oxidize metallic silver?

(c) Will metallic silver reduce solid iodine?

(d) Will VO2+

oxidize manganese (II) ions to manganese (IV) oxide?

(e) Will metallic lead in a sulfate solution reduce solid iodine?

(f) Will silver ions oxidize VO2+

?

(g) Will manganese (IV) oxide oxidize iodide ions?

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EXTRA HOMEWORK 3E

1. Consider the cell

Mn (s) | Mn2+

(0.10 M) || Fe2+

(1.0 M) | Fe (s)

(a) Write the spontaneous chemical reaction that takes place in this cell

(b) Which metal, Mn or Fe, will be the anode, and which metal will be the cathode?

(c) What is Ɛº for the cell?

(d) What is Ɛ for the cell at 298 K with the concentrations specified above?

2. A silver-magnesium battery is set up under standard conditions with all species at unit activity. Initially,

the voltage developed by this cell is 3.17 V. As the battery is used, the concentration of the silver ion

gradually decreases, and that of the magnesium ion increases.

(a) Calculate the ratio of activities of products to reactants, Q, when the cell voltage is 3.00 V at 298 K.

(b) Calculate the ratio of activities of products to reactants, Q, when the cell voltage is 0.00 V at 298 K.

3. Consider the cell

Mg (s) | Mg2+

(0.0010 M) || Ag+

(0.0010 M) | Ag (s)

for which Ɛº = 3.17 V. Does the cell voltage increase, decrease, or remain the same when each of the

following changes is made?

(a) The given magnesium electrode is replaced by a larger magnesium electrode.

(b) Excess 1.0 M sodium hydroxide is added to the anode compartment

(c) Excess 1.0 M ammonia is added is added to the cathode compartment.

4. Find the standard reduction potentials for these following half reactions from Table 18.1:

SO42-

(aq) + 4H+

(aq) + 2e- → H2SO3 (aq) + H2O (l) Ɛ° =

Ag+

(aq) + e- → Ag (s) Ɛ° =

Assuming all reactants and products are at unit activity,

(a) Write the balanced overall reaction for a successful cell made from these two couples.

(b) What is Ɛ° for the cell?

(c) What is the equilibrium constant for the reaction at 25°C?

(d) Calculate the ratio of activities of products to reactants, Q, which will produce a cell voltage of 0.51

V at 25°C?

5. A standard cell at 298 K is composed of a Mg | Mg2+

(1 M) half-cell and a Ni | Ni2+

(1 M) half-cell.

(a) Determine the spontaneous chemical reaction that takes place in this cell.

(b) What is Ɛ º for the cell?

(d) If the Ni2+

concentration drops to 0.50 M and is maintained there, calculate the concentration of

Mg2+

ions in the cell when the voltage is 2.10 V.

(continued on next page)

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6. Consider a standard cell composed of an Au | Au

3+ (1 M) half-cell and a Ag | Ag

+ (1 M) half-cell.

(a) Determine the spontaneous chemical reaction that takes place in this cell.

(a) What is Ɛº for the cell at 298 K?

(c) Calculate the voltage of a different cell at 298 K when [Au3+

] = 1.000 M and [Ag+] = 0.000 M

(d) Calculate the voltage of the cell in (c) when 10.% of the Au3+

has reacted away.

(e) Calculate the voltage of the cell in (c) when 50.% of the Au3+

has reacted away.

(f) Calculate the voltage of the cell in (c) when 99% of the Au3+

has reacted away.

*7. A standard hydrogen half-cell is coupled to a standard zinc half-cell. H2S gas is bubbled into the zinc

half-cell, causing precipitation of ZnS, until a concentration of 1.14 M S2-

is reached. The voltage of the

cell at this point is 1.40 V.

(a) What is Ɛ° for the hydrogen-zinc cell?

(b) What is the concentration of the zinc ions in the cell when the voltage is 1.40 V?

(c) What is the Ksp for zinc sulfide?

*8. A standard hydrogen half-cell is coupled to a standard silver half-cell. Sodium bromide is added to the

silver half-cell, causing precipitation of AgBr, until a concentration of 1.00 M Br- is reached. The

voltage of the cell at this point is 0.072 V.

(a) What is Ɛº for the hydrogen-silver cell?

(b) What is the concentration of the silver ions in the cell when the voltage is 0.072 V?

(c) What is the Ksp for silver bromide?

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EXTRA HOMEWORK 3F

1. Give the electrolysis products at the anode and cathode for each of the following liquids or solutions.

(a) KCl (l) (b) KCl (aq) (c) AuCl3 (l) (d) AuCl3

(aq)

(a) KNO3 (aq) (b) Au(NO3)3 (aq) (c) HCl (aq) (h) HNO3 (aq)

2. Give the anode and cathode half-reactions that take place in questions 1a and 1b.

3. How many grams of metallic magnesium can be obtained by passing a current of 5.00 A through molten

magnesium chloride for 3.00 hours?

4. Electricity is passed through an aluminum nitrate solution for 45 minutes, depositing 0.126 g of

aluminum on the cathode. How many amperes was the current?

5. An aqueous solution of gold (III) nitrate is electrolyzed by passing a current of 10.0 A through an

electrolysis cell for a certain length of time. In this process 12.5 g of gold are deposited on the cathode.

(a) What is the half-reaction that occurs at the cathode?

(b) What is the half-reaction that occurs at the anode?

(c) How long does the process take?

(d) What mass of oxygen gas is liberated at the anode?

EXTRA 3A ANSWERS

1. (a) -203 kJ (b) -198 kJ

2. (a) liquid water (b) gaseous propane (c) lead (d) aqueous Mg(NO3)2

3. (a) +, increase (b) -, decrease (c) -, decrease (d) +, increase

4. (a) positive (b) negative (c) negative (d) positive

(e) positive (f) negative

5. 82 kJ/mol; the change in enthalpy (or the amount of heat absorbed) when one mole of NO2 (g) is formed

under standard conditions via the following reaction: ½N2 (g) + O2 (g) N2O (g)

6. 220 J/molK; the amount of entropy (or disorder) contained in one mole of NO2 (g) under standard

conditions

7. (a) -167 J/K (b) 103 J/K

*8. 1/16

*9. 1/256

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EXTRA 3B ANSWERS

1. (a) can’t be determined (b) nonspontaneous (c) spontaneous (d) can’t be determined

2. 104 kJ/mol; the change in Gibbs free energy (or the amount of energy available for work, or the

direction of spontaneity) for the reaction: ½N2 (g) + O2 (g) ⇆ N2O (g) when a reaction vessel contains

one-half mole of N2 (g), one mole of O2 (g), and one mole of NO2 (g) under standard conditions

3. (a) 100. kJ (b) 138 J/K (c) 53 kJ (d) 59 kJ (≈ 53 kJ)

(e) no (f) ∆H against, ∆S for (g) more

4. (a) 173 kJ, 188 kJ, 0.050 J/K (b) 83 J/molK

(c) 173 kJ, 0.050 J/K, 153 kJ

5. (a) 5.6 kJ, reverse (b) -0.1 kJ, forward (c) 352 K = 78ºC

*6. (a) 8.65 kJ, reverse (b) -5.71 kJ, forward (c) 433 K or 160.ºC

*7. (a) -536 kJ (b) 4C (s) + 4H2 (g) + O2 (g) → C3H7CO2H (l)

(c) -527 J/K (d) -379 kJ

EXTRA 3C ANSWERS

1. (a) -6 kJ (b) 1 kJ, no left (c) 0 kJ, no shift (d) -6 kJ, shift right

2. (a) -34 kJ (b) yes (c) >1 (d) 9.1 x 105

(e) products (f) more spontaneous

3. (a) -1324 kJ (b) yes (c) >1 (d) 8.49 x 10231

or e534

(e) products (f) less spontaneous (g) more spontaneous

4. (a) 19.4 kJ (b) no (c) <1 (d) 3.98 x 10-4

(e) almost identical: 3.98 x 10-4

≈ 4.0 x 10-4

(f) -9.1 kJ (g) yes

5. (a) Ka = [H3O+][C6H5CO2

-]/[C6H5CO2H] (b) 8.0 x 10

-3 M (c) 2.10

(d) >0 (e) 24 kJ

6. (a) 1.2 x 10-10

, 8.4 x 10-10

(b) 28 kJ, -96 J/K

*7. -15 kJ/mol

*8. (a) -115 kJ (b) -151 kJ (c) -0.120 kJ/K (d) 1.50 X 1020

(e) Keq will decrease with increasing T

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EXTRA 3D ANSWERS

1. (a) spontaneous (b) nonspontaneous (c) nonspontaneous (d) spontaneous

2. (a) Zn + Sn2+

→ Zn2+

+ Sn (b) 0.62 V

(c) anode Zn, cathode Sn (d) Zn to Sn

3. (a) 3Ba + 2Cr3+

→ 3Ba2+

+ 2Cr (b) 2.17 V

(c) anode Ba, cathode Cr (d) Ba to Cr

4. (a) MnO2 ox. agent, Pb with SO42-

red. agent (b) yes (c) no

(d) no (e) yes (f) no (g) yes

EXTRA 3E ANSWERS

1. (a) Mn + Fe2+

→ Mn2+

+ Fe (b) Mn anode, Fe cathode

(c) 0.74 V (d) 0.77 V

2. (a) 5.6 x 105 (b) 1.43 x 10

107 or e

247

3. (a) remain the same (b) increase (c) decrease

4. (a) H2SO3 + H2O + 2Ag+ → SO4

2- + 4H

+ + 2Ag (b) 0.60 V

(c) 1.9 x 1020

(d) 1000

5. (a) Mg + Ni2+

→ Mg2+

+ Ni (b) 2.14 V (c) 11 M

6. (a) 3Ag + Au3+

→ 3Ag+ + Au (b) 0.70 V (c) V

(d) 0.73 V (e) 0.68 V (f) 0.63 V

*7. (a) 0.76 V (b) 2.3 x 10-22

(c) 2.6 x 10-22

*8. (a) 0.80 V (b) 5.0 x 10-13

M (c) 5.0 x 10-13

M

Page 13: EXTRA HOMEWORK 3A - Saddleback College · EXTRA HOMEWORK 3A 1. ... The standard enthalpy change of combustion for butyric acid at 298 K is -2,184 ... -ion in a 1.00 M solution of

EXTRA 3F ANSWERS

1. (a) Cl2 (g), K (s) (b) Cl2 (g), H2 (g) (c) Cl2 (g), Au (s) (d) Cl2 (g), Au (s)

(d) O2 (g), H2 (g) (f) O2 (g), Au (s) (g) Cl2 (g), H2 (g) (h) O2 (g), H2 (g)

2. (a) anode – 2Cl- → Cl2 + 2e

- cathode – K

+ + e

- → K

(b) anode – 2Cl- → Cl2 + 2e

- cathode – 4H2O + 4e

- → 2H2 + 4OH

-

3. 6.80 g

4. 0.50 A

5. (a) Au3+

+ 3e- → Au (b) 2H2O → O2 + 4e

- + 4H

+

(c) 30.6 min (d) 1.52 g