كيمياء كهربىة لطلاب برنامج فيزياء الطاقة - Choose the correct answer

1-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

(e) cannot tell unless we know the species being oxidized and reduced.

2. 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.

3- The half-reaction that occurs at the anode during the electrolysis of molten sodium bromide is:(a) 2 Br^-  Br₂ + 2 e^-(b) Br₂ + 2 e^-  2 Br^-(c) Na⁺ + e^-  Na(d) Na  Na⁺ + e^-(e) 2 H₂O + 2 e^-  2 OH^- + H₂

4-Which of the following is the strongest oxidizing agent?

(a) Pb²⁺

(b) I₂

(c) Ag⁺

(d) Pb

(e) Cu²⁺

5- 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.

6-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

 7-Which of the following statements is(are) true for all voltaic (or galvanic) cells?

(I) Reduction occurs at the cathode.

(II) The anode gains mass during discharge (note: this means operation of the cell.)

(III) The voltage is less than or equal to zero.

(a) only III

(b) only II

(c) only I

(d) II and III

(e) I, II, and III

 8-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