Electrochemistry

Do you know what electrochemistry is? It is a branch of chemistry that converts chemical energy to electrical energy and vice versa. An electrochemical cell is a device that produces energy from electrochemical reactions. Electrochemical reactions occur in galvanic cells or Daniel cells, which are electrochemical cells.

There are two important cells of electrochemistry - the electrochemical cell and the electrolytic cell. The voltage of the cell changes with a change in the electrolyte concentration. To know more about this experiment, continue reading this article!! 

Table of Content

• Aim

• Apparatus Required

• Theory

• Procedure

• Observation

• Result

• Precautions

Aim

To study the variation of cell potential with a change in concentration of electrolyte at room temperature. 

Apparatus Required

Following are some of the important apparatus required for this experiment

• Glass beaker

• Porous pot

• Zinc strip

• Copper strip 

• Voltmeter

• 0.1M ZnSO4

• 0.1 M CuSO4

Theory

Electrochemistry is the branch of chemistry that deals with the relationship between electrical changes and chemical changes. Electrochemical reactions are reactions that convert chemical energy into electrical energy, and it is a spontaneous reaction. These reactions occur in a galvanic cell. Here the zinc electrode will act as an anode, and the copper electrode will act as a cathode. On zinc electrodes, Oxidation takes place, and on copper electrodes, reduction takes place.

Daniel's cell

Procedure

The following are the important steps that need to be followed:

• First, take the CuSO4 solution in a beaker and place a copper strip in it

• Now add 100 ml zinc sulfate solution in a beaker and dip a zinc strip in it 

• Now connect the zinc strip with the negative terminal and the copper strip with the positive terminal of the voltmeter.

• After connecting the strips with the voltmeter current starts to flow carefully, observing the reading of the voltmeter, which denotes the emf of the cell. 

• Repeat the above experiment by changing the concentration of zinc sulfate solution but keeping the concentration of copper sulfate the same. 

• Now again, repeat the above experiment by changing the concentration of copper sulfate and keeping the zinc sulfate concentration unchanged. 

Observations

Results

The observed table and calculated emf from the first equation are the same. 

The following formula can calculate Emf: Ecell = E°cell - RT logQ/nF

Where E is the emf of the cell,

E° is the standard emf of a cell

F is Faraday's constant. 

Precautions

Following are some precautions that need to be followed while experimenting.

• Copper and zinc strips must be cleaned with Sandpaper to remove dust 

• Reading of the voltmeter should be noted when the pointer becomes stable

• The connections must be tight

• Both the beaker and the porous pot must be washed and rinsed. 

Lab Manual Questions

Q1 Define electromotive force.

Ans: Electromotive force is defined as the potential difference which leads to the flow of current from cathode to anode in an electrochemical cell.

Q2 What is oxidation?

Ans: Oxidation is defined as the process of losing an electron.

Q3 What is the difference between an electrochemical cell and an electrolytic cell?

Ans: In an electrochemical cell, chemical energy is converted to electrical energy, whereas in an electrolytic cell, electrical energy is converted to chemical energy. 

Viva Questions

Q1 What is electrochemical series? 

Ans: It is a series of elements arranged based on their increasing or decreasing standard reduction potential.

Q2 What is the importance of electrochemical series?

Ans: It helps us to know oxidising and reducing power of elements.

Q3 What do you mean by electrolysis

Ans: Electrolysis is converting electrical energy into chemical energy.

Q4 How can you define molar conductance?

Ans: Molar conductance is defined as the conduction of a one-mole solution placed between two parallel electrodes one centimetre apart.

Q5 What is kohlrausch law?

Ans: This law states that the limiting molar conductivity of an electrolyte is the sum of its cation and anion.

Q6 What is the difference between a primary battery and a secondary battery?

Ans: The primary battery is irreversible, whereas the secondary battery is a reversible type of battery.

Q7 How Can you define resistance?

Ans: Resistance is defined as the obstruction to current flow.

Q8 What is electrochemistry?

Ans: It deals with the study of the conversion of chemical energy to electrical energy. 

Practical-Based Questions

Q1 In Which direction do electrons move in an electrochemical cell?

1. Cathode to anode

2. Anode to cathode

3. Both of the above

4. None of the above

Ans: 2. Anode to the cathode

Q2 Which of the following is the anode of Daniel's cell

1. Zinc rode

2. Copper rode

3. Both of the above

4. None of the above

Ans: 1. Zinc rode 

Q3 Can we store copper sulphate solution in a zinc pot

1. Yes

2. No

3. May be stored

4. None of the above

Ans: 2. No

Q4 The value of equivalent conduction

1. Increases on dilution

2. Decreases on dilution 

3. Remains the same on dilution

4. None of the above

Ans: 1. Increases in dilution

Q5 The value of specific conduction

1. Increases on dilution

2. Remains the same on dilution

3. Decreases on dilution

4. None of the above

Ans: 3. Decreases in dilution

Q6 Corrosion is an 

1. Physical reaction

2. Chemical reaction

3. Electrochemical reaction

4. None of the above

Ans: 3. Electrochemical reaction 

Q7 A species of higher standard reduction potential will

1. Undergo oxidation

2. Undergo reduction

3. Remain same

4. None of the above

Ans: 2. Undergo reduction

Q8  What is the standard reduction potential of the zinc electrode 

1. 0.37

2. 0.76

3. 0.6

4. 0.56

Ans: 2. 0.76.

Conclusion

• In this article, we have studied electrochemistry experiments and the electrochemistry formula.

• We have also discussed the change in voltage on changing the concentration of the solution.

• The steps of the experiment and articles required for conducting this experiment have also been discussed here.

• Certain precautions which must be followed while experimenting have also been discussed.