Electrode Potential and its Measurement Objective: To measure the electrode pote

Question

Electrode Potential and its Measurement

Objective:

To measure the electrode potential and Redox potential of various metals & alloys using calomel reference electrode (SCE).

Experimental Procedure:

I. Measurement of electrode potential:

1.   Prepare two small cylindrical specimens one made from Carbon Steel (CS) and the other made from Stainless Steel (SS), so as to fit the specimen holder of spherical ASTM flask. -

2.   Immerse each of the small cylindrical specimen (SS and CS) in the ASTM flask containing tap water, and brine respectively.

3    Using the digital voltmeter and a Saturated Calomel Reference Electrode (SCE), measure the potential of the SS in tap water, and in brine. Also measure the potential of the CS in same two environments.

II. Measurement of Potential in standard and non-standard conditions:

[Verification of Nernst Equation]

1.Prepare 1-M solutions of Zn+2 and Cu+2.

2.Measure the potential E0 (Zn / Zn+2 ) and E0 (Cu / Cu+2 ) in standard condition using Saturated Calomel Reference Electrode (SCE).

Measure the potential E (Zn / Zn+2 ) and E (Cu / Cu+2 ) in non-standard condition (0.5-M solutions) using Saturated Calomel Reference Electrode (SCE)

1.Determine the potentials measured in non-standard condition using Nernst Equation given below:

E = E0 + (0.0592 / n) log (Cion) Where E0 = standard electrode potential

                                 n = number of electrons transferred

                                              Cion = concentration of metal in molar units

Explanation / Answer

Introduction

The current experiment is to determine the redox potential of given metals (zinc and copper )and alloys (stainless steel and carbon steel) by using calomel electrode.

The calomel electrode has a redution potential of 0.241 with respect of SHE.

so calomel electrode is a cathode when coupled with SHE.

The potential was measured in different conditions like tap water, brine water and in their own metal solutions.

For the experiment we need standard solution of metal ions (Zn and Cu)

Conclusion

Intutively good results were obtained for the experiment. The standard electrode used was Calomel electrode. The experminet signifies that the following are good reducing agents

a) Stainless steel in both tap and brine water [Negative electrode potential with respect ot calomel electrode]

b) Carbon steel in both tap and brine water

c) Standard and seminormal solution of Zn+2

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