Electrochemistry Review

Voltaic Cell

100

The voltaic cell in which the reduction reaction occurs.

What is a cathode?

200

Determine in a galvanic cell in which cell the following reaction will occur: Zn(s) → Zn²⁺(aq) + 2e-

A: What is the reaction that occurs in the anode?

300

Ion that moves toward the anode from the salt bridge

A: What is anion?

400

In the following reaction, determine the electrode which gains mass:

Zn(s) +Cu²⁺(aq) → Zn²⁺(aq) + Cu(s)

A: What is the Cu (s) electrode.

500

Write the shorthand notation for the redox reaction given below.

Sn(s) + 2H⁺(aq) → Sn²⁺(aq) + H₂(g)

A: Sn(s) | Sn²⁺(aq) || H⁺(aq) | H₂(g) | Pt

Redox Reactions

100

Determine the change in the oxidation number of Hg and N:

2Hg²⁺(aq) + N₂H₄(aq) → 2Hg(l) + N₂(g) + 4H⁺(aq)

A. Hg: 2+ to 0 B. N: –2 to 0  

200

In the following balanced equation,

6I^-(aq) + 14H₃O⁺(aq) + Cr₂O₇^2-(aq) →                                                     2Cr³⁺(aq) + 21H₂O(l) + 3I₂(s)

the reducing agent is

A: What is I^1-

300

Complete and balance the following half-reactions. Determine whether oxidation or reduction occurs.

TiO₂ (s) → Ti²⁺ (aq) in an acidic solution

A: What is 

TiO₂(s) + 4H⁺ (aq) + 2e- → Ti²⁺ (aq) + 2H₂O(l) reduction

400

Complete and balance the following half-reactions. Determine whether oxidation or reduction occurs.

MnO41- → MnO2

A: MnO₄^1- + H₂O → MnO₂ + 4OH^1-

500

Complete and balance the following half-reactions. Determine whether oxidation or reduction occurs. La(s) ---> La(OH)₃ (s) in a basic solution

What is A. La(s) + 3OH^- (aq) ---> La(OH)₃ (s) + 3e^- B. oxidation

Cell EMF

100

Given the following reaction and that the standard reduction potential of Zn2+ is –0.76V , determine the Eored for the reduction of Cu+2 to Cu

Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s)    E^o_cell = 1.10V

A: What is Anode: Cd(s) → Cd²⁺ (aq) + 2e-

Cathode: Sn²⁺ (aq) + 2e- → Sn(s)

200

Given the following equation and standard reduction potentials, determine E^o_cell  

Zn(s) + 2H⁺(aq) → Zn²⁺(aq) + H₂(g)

2H⁺(aq) + 2e- → H₂(g);  E^o_red = 0.0 V

Zn²⁺(aq) + 2e- → Zn(s); E^o_red = –0.76V

What is E^o_cell = +0.76V

300

Given the following reaction and that the standard reduction potential of Zn⁺² is -0.76V , determine the E^o_red for the reduction of Cu⁺² to Cu 

 Zn(s) + Cu²⁺(aq) ---> Zn²⁺(aq) + Cu(s)  

E^o_cell=1.10V

What is 0.34V

400

Determine whether or not this reaction                             Cl₂(g) +2I^1- → I₂(s) + 2Cl^1-

is spontaneous given:

Cl₂(g) + 2e- → 2Cl-(aq)   E^o = +1.36V

2I-(aq) → I₂(s) +2e-       E^o = +0.54V

A: What is spontaneous?

500

Given the following E^o_red values, determine if NO₃^-, Ag⁺, or Cr₂O₇^2- is the strongest oxidizing agent

NO₃^- + 4H⁺+3e- → NO + 2H₂O;     E^o_red = +0.96V

Ag⁺(aq) + e- → Ag(s);                  E^o_red = +0.80V

Cr₂O₇^2- +14H⁺ +6e- → 2Cr³⁺+7H₂O;E^o_cell = 1.33V

A: What is Cr₂O7^2-?

Nernst

100

In galvanic cell in which the following reaction occurs

Zn(s) + 2H⁺(g) → Zn²⁺ + H₂(g)  

the addition of H₂SO₄ to the cathode cell will cause the Eo to increase/decrease and shift the equilibrium to the reactants/products.

A: increase, products

200

If a cell is created in which Q > K it will cause the E cell to increase/decrease and shift the equilibrium to the reactants/products.

A: What is decrease, reactants

300

Given that E°red = –0.40 V for Cd²⁺/Cd at 25°C, find E for the concentration cell expressed using shorthand notation below.

Cd(s) | Cd²⁺(1.0 × 10^-5 M) || Cd²⁺(0.100 M) | Cd(s)

A: What is E = +0.12 V

400

Calculate the cell potential for the following reaction that takes place in an electrochemical cell at 25°C.

Sn(s) | Sn²⁺(aq, 1.8 M) || Ag⁺(aq, 0.055 M) | Ag(s)

Ag⁺ (aq) + e-  → Ag (s)               E° = +0.800 V

Sn²⁺ (aq) + 2 e- →  Sn(s)            E° = –0.14 V

A: What is +0.86 V

500

What is the [Cu²⁺] in the cell                                  Zn / Zn²⁺ (0.05 M) || Cu²⁺ (? M) / Cu

if the cell voltage is 1.03 V?

Zn²⁺ + 2e- → Zn     E^o = –0.763 V                             Cu²⁺ + 2e- → Cu    E^o  = 0.337 V

A: What is A: 0.0002 M

Misc

100

Given: Mg²⁺ + 2e− → Mg          Eº = −2.37 V

            Fe³⁺ + 1e− → Fe2+      Eº = −0.77 V

When the reaction Mg + Fe³⁺ → Fe²⁺ + Mg²⁺ comes to equilibrium, the Ecell value becomes

A: What is 0.00 V

200

Given the standard electrode potentials:

Ni²⁺ + 2e- → Ni (s)     E^o = –0.23 V;

Cr³⁺ + 3e- → Cr (s)     E^o = –0.74

Which pair of substances will react spontaneously?

A: What is Ni²⁺ with Cr

300

In the electroplating of silver from cyanide solution, the cathode reaction is:

Ag(CN)₂⁺ + e- → Ag(s) + 2CN^-

How many grams of silver should be deposited by a current of 4.50 A in 28.0 minutes?

A: What is 8.45 g

400

10.0 amps are passed through molten aluminum chloride for 5.50 hours. How many grams of aluminum metal could be produced by this electrolysis?

A: What is 18.5 g

500

Calculate ∆G^o in kJ/mol for the reaction             4Ag(s) + O₂(g) + 4H⁺ (aq) → 4Ag⁺(aq) + 2H₂0(l)

Given

O₂(g) + 4H⁺(aq) + 4e- → 2H₂0(l); E^o_red = +1.23V

Ag⁺(aq) + e- → Ag(s) ;                E^o_red= +0.80V

A: What is –170 kJ/mol