problem solving

Definitions

For each of the following balanced half-reactions, determine whether an oxidation or reduction is occurring.

1. Fe3+ + 3e‑ ⟶ Fe

2. Cr⟶Cr3+ + 3e‑

3. MnO42- ⟶MnO4-  +  e‑

4. Li+ + e‑  ⟶Li

Balancing with ½ reaction method

Given the following pairs of balanced half-reactions or unbalanced reactions, determine the balanced reaction for each pair of half-reactions in an acidic solution and in a basic solution. Identify the species that undergoes oxidation, the species that undergoes reduction, the oxidizing agent, and the reducing agent in each of the reactions below.

1. Ca⟶Ca2+ +2e e‑,F2+2 e‑ ⟶ 2F−

2. Fe2+ (aq) + MnO4-(aq) ⟶ Fe3+(aq) + Mn2+(aq) 

3. Cu(s) + NO3-(aq) ⟶ Cu2+(aq) + NO2(g)

4. Ag⟶Ag++ e‑  , MnO4-+ 4H+ + 3  e‑  ⟶MnO2+2H2O

e.       SO32-(aq) + Cu(OH)2(s)⟶SO42-(aq)+Cu(OH)

f.        Al(s)+CrO42-(aq)⟶Al(OH)3(s)+Cr(OH)4-(aq)

Galvanic Cells and Spontaneity

Write the following balanced reactions using cell notation. Use platinum as an inert electrode, if needed.

1. Mg(s) + Ni2+(aq)⟶Mg2+(aq) + Ni(s)

2. 2Ag+(q)+Cu(s)⟶Cu2+(aq) + 2Ag(s)

3. Mn(s)+Sn(NO3)2(aq)⟶Mn(NO3)2(aq) + Sns)

Given the following cell notations, determine the species oxidized, species reduced, and the oxidizing agent and reducing agent, without writing the balanced reactions.

1. Mg(s)│Mg2+(aq)║Cu2+(aq)│Cu(s)

2. Ni(s)│Ni2+(aq)║Ag+(aq)│Ag(s)

For each reaction listed, determine its standard cell potential at 25 °C and whether the reaction is spontaneous at standard conditions.

1. Mn(s) 7+ Ni2+(aq)⟶Mn2+(aq) + Ni(s)

2. 3Cu2+(aq) + 2Al(s)⟶2Al3+(aq) + 2Cu(s)

3. Na(s) + LiNO3(aq)⟶NaNO3(aq) + Li(s)

Nernst Equation

For the standard cell potentials given here, determine the ΔG° for the cell in kJ.

1. 0.000 V, n = 2

2. +0.434 V, n = 2

3. −2.439 V, n = 1

For the ΔG° values given here, determine the standard cell potential for the cell.

1. 12 kJ/mol, n = 3

2. −45 kJ/mol, n = 1

For the following reaction at nonstandard conditions, is the process spontaneous? 

Co(s)+Fe2+ (aq,1.94M)⟶Co2+ (aq, 0.15M)+Fe(s)

 Is it spontaneous at the following conditions? [Fe2+] = 150.5M, [Co2+] = 0.00015M