Homework Answers

7. Consider the following half-reactions:

Half-Reaction E0 (V)  MnO4(aq) + 8 H+ + 5 e

- Mn

2+ + 4 H2O +1.52

2 C 2O7(aq) r + 14 H+ + 6 e

- Cr

3+ + 7 H2O +1.33  B 3(aq) rO + 6 H+ + 6 e

- 𝐵− + 3 H2O +1.47

2 SO4(aq) + 4 H+ + 2 e

- SO2(g) + 2 H2O +0.2  NO3(aq) + 4 H+ + 3 e

- NO(g) + 2 H2O + 0.96

(a) Identify the strongest oxidizing agent and the strongest reducing agent. (b) Which of the oxidizing agents listed is / are capable of oxidizing 𝐵−

to  B 3(aq) rO in acidic solution. (c) Write a balanced chemical equation for the reaction of 2 C 2O7(aq) r and

SO2(g) in acid medium. Is this reaction spontaneous?

(d) Write a balanced chemical equation for the reaction of 2 C 2O7(aq) r with

Mn

2+

(aq) in acid medium. Is this reaction spontaneous?

3. Calculate the maximum work available from 50.0 g of aluminum in the following

cell when the cell potential is 1.15 V. Al(s) |Al3+

(aq) || H+

(aq) | O2(g) |Pt . Note that O2 is reduced to H2O. Use appropriate standard reduction potentials

13. Consider the lead acid battery. a) What class of battery is it and what distinguishes it from the other

classes of batteries?

b) Give the cell notation for the lead acid battery. c) Write the half reactions and the discharging reaction of the battery. d) If each cell in the battery has an output of approximately two volts, draw a labelled sketch diagram of a battery with a six volt output. On

the diagram indicate the anode and the cathode. Name one characteristic of an ideal lead-acid battery.

11. Compare and contrast the electrolytic and voltaic cell.

10. Tin is used to coat tin cans for food storage. If the tin is scratched and the iron of

the can exposed, will the iron corrode more rapidly or less rapidly? Explain

9. Construct a galvanic cell using the following reactions. Look up E° values

(a) MnO4 (aq)

- + e

- → MnO4

2-

(aq)

(b) Zn

2+

(aq) + 2e- → Zn(s)

(i) What type of electrodes are used at the anode and cathode and why?

(ii) Write the reaction at the anode and cathode

(iii) Write the overall reaction and calculate the cell potential

(iv) Write the line notation for the reaction above

6. Give the balanced full reaction and calculate the E° for galvanic cells based on the

following reactions. Draw diagrams indicating; the anode, cathode, flow of electrons, salt bridge

(a) Zn

2+

(aq)+ 2e

-  Zn (s)

Pb

2+

(aq) + 2e

-  Pb(s)

(b) Cr2O7

- + 14H+ + 6e

-  2Cr

3+ + 7H2O

H2O2 + 2H+ + 2e

-  2H2O

In a titration experiment, an average of 15.2 mL of a 0.25 mol/L NaOH solution was needed to neutralize 20.0 mL of an unknown concentration of HCl. What is the molar concentration of the HCl solution?

A 50.0 mL solution of H₂SO₄ has a concentration of 2.00 mol/L. It is dilutedby adding 150mL of water. What is the molar concentration of the sulphuric acid after dilution?

Ammonia (NH₃) will react with water and cause phenolphthalein to turn pink. Using the Bronsted-Lowry Theory of acids and bases to write balanced equation of this reaction. Also, indicating each component as an acid, base, conjugate acid, or conjugate base.