Q3 of 7 Page 84

You are given a solution of AgNO3, a solution of MgSO4, an Ag rod and an Mg ribbon. How can you arrange a Galvanic cell using these? Write down the reactions taking place at the cathode and the anode.

First we take 100 ml solution of MgSO4 in one beaker and 100 ml solution of AgNO3 in the second beaker. Immerse Mg ribbon in MgSO4 solution and Ag rod in AgNO3 solution. Connect the negative terminal of a voltmeter to the Mg ribbon and positive terminal to the Ag rod. Connect the solutions in two beakers by a salt bridge.

Oxidation will occur at anode and reduction will occur at the cathode.

Reaction at anode - Mg(s) Mg2+(aq) + 2e-

Reaction at cathode - Ag+(aq) + e-Ag(s)

Mg(s) + 2Ag+(aq) Mg2+(aq) + Ag(s)

Note- Salt bridge is a U-tube filled with a paste made by mixing gelatin or agar gel and a salt like KCl or KNO3. This completes the circuit by transfer of ions and maintains the electrical neutrality of the cell.

More from this chapter

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1

The solutions of ZnSO4, FeSO4, CuSO4, and AgNO3 are taken in four different test tubes. Suppose, an iron nail is kept immersed in each one.

• In which test tube the iron nail undergoes a colour change?


• What is the reaction taking place here?


• Justify your answer. (Refer reactivity series of metals).

 2

Compare the electrolysis of molten potassium chloride and solution of potassium chloride. What are the processes taking place at the cathode and the anode?

 1

Keep two carbon rods immersed in a copper sulphate solution. Then pass electricity through the soon.

(i) At which electrode does a colour change occur-anode or cathode?


(ii) Is there any change in the blue colour of the copper sulphate solution?


(iii) Write down the chemical equations for the changes occurring here.

 2

When acidified copper sulphate solution is electrolyzed oxygen is obtained at the anode. What arrangements are to be made for this? Find the element deposited at the cathode.