ELECTROCHEMISTRY

Ag+(aq) + e– → Ag(s) E° = + 0.80 V

Fe2+(aq)+ + 2e– → Fe(s) E° = – 0.44 V

What is emf of

Fe(s) + 2Ag+(aq) → Fe2+(aq) + 2Ag(s)

• (a) 1.16 V

• (b) 1.24 V

• (c) 2.04 V

• (d) -1.16 V

In an electrolytic cell the electrode at which the electrons enter the solution is called the ______ ; the chemical change that occurs at this electrode is called _______.

• (a) anode, oxidation

• (b) anode, reduction

• (c) cathode, oxidation

• (d) cathode, reduction

Which of the following statements is FALSE?

• (a) Oxidation and reduction half-reactions occur at electrodes in electrochemical cells.

• (b) All electrochemical reactions involve the transfer of electrons.

• (c) Reduction occurs at the cathode.

• (d) Oxidation occurs at the anode.

• (e) All voltaic (galvanic) cells involve the use of electricity to initiate nonspontaneous chemical reactions.

As the cell given below operates, the strip of silver gains mass (only silver) and the concentration of silver ions in the solution around the silver strip decreases, while the strip of lead loses mass and the concentration of lead increases in the solution around the lead strip. Which of the following represents the reaction that occurs at the negative electrode in the above cell?

Pb / Pb(NO₃)₂ (1.0 M) || AgNO₃ (1.0 M) / Ag

• (a) Pb²⁺ + 2 e^- Pb

• (b) Pb Pb²⁺ + 2 e^-

• (c) Ag⁺ + e^- Ag

• (d) Ag Ag⁺ + e^-

• (e) none of the above

In the standard notation for a voltaic cell, the double vertical line "||" represents:

• (a) a phase boundary

• (b) gas electrode

• (c) a wire (metal) connection

• (d) a salt bridge

• (e) a standard hydrogen electrode

In voltaic cells, such as those diagrammed in your text, the salt bridge _______ .

• (a) is not necessary in order for the cell to work

• (b) acts as a mechanism to allow mechanical mixing of the solutions

• (c) allows charge balance to be maintained in the cell

• (d) is tightly plugged with firm agar gel through which ions cannot pass

• (e) drives free electrons from one half-cell to the other

What is the reduction potential for the half-reaction at 25^o C:

Al³⁺ + 3e^- Al, if [Al³⁺] = 0.10 M and E^o = -1.66 V ?

• (a) -1.84 V

• (b) -1.60 V

• (c) -1.68 V

• (d) -1.66 V

• (e) -1.72 V

For a voltaic (or galvanic) cell using Ag,Ag⁺ (1.0 M) and Zn,Zn²⁺ (1.0 M) half-cells, which of the following statements is incorrect?

• (a) The zinc electrode is the anode.

• (b) Electrons will flow through the external circuit from the zinc electrode to the silver electrode.

• (c) Reduction occurs at the zinc electrode as the cell operates.

• (d) The mass of the zinc electrode will decrease as the cell operates.

• (e) The concentration of Ag⁺ will decrease as the cell operates.

Which statement is correct about the Daniell cell?

• The Daniell cell is an example of an electrolytic cell.

• The spontaneous cell reaction involves the oxidation of Cu by Zn2+.

• The spontaneous cell reaction involves the reduction of Zn2+ to Zn.

• The spontaneous cell reaction involves the reduction of Cu2+ to Cu.

The difference between the electrode potentials of two electrodes when no current is drawn through the cell is called ___________.

• (i) Cell potential

• (ii) Cell emf

• (iii) Potential difference

• (iv) Cell voltage