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Electrochemistry- Voltaic cell

Key words: Electrochemistry, Voltaic cell, Battery, Redox reaction, Half cell reaction.

Essential question: Can we produce electricity from chemical reactions ?

Electrochemistry- Voltaic cell

Definition of Electrochemistry

Electrochemistry is a part of chemistry that study the production of electricity from chemical reactions such as oxidation and reduction reactions which involve transfer of electrons. the movement of electrons from one element to another inside a wire can produce electricity.

Potato Battery

Do you know that we can form a battery using potato ??

Electrochemistry- Voltaic cell

To make a potato battery the needed materials are :

  • A wire
  • Some potatoes
  • Zinc nails
  • Copper nails
  • A voltmeter or a low voltage LED light to test if the battery in generating electricity.

To form this battery we need to begin by putting one zinc nail and one copper nail into the potato. Then we connect these two nails to the voltmeter using a wire and crocodile clips. The voltmeter give a value, so an electricity is produced, the potato battery is generating power. Now if we need to generate more power we should use more potatoes. Other fruits or vegetables can be used like carrots or oranges…

Voltaic cell

A voltaic cell is an electrochemical cell that produce electricity using Redox reactions. This cell is made by putting two different metals in two separated solutions, and linking them using a slat bridge.

The needed materials to form a voltaic cell are :

  • Zinc metal
  • Copper metal
  • 1 M of zinc sulfate solution
  • 1 M of copper (II) sulfate solution
  • A wire and crocodile clips
  • A Voltmeter
  • 2 Beakers
  • A salt bridge

To form this voltaic cell start by putting the zinc metal in the zinc sulfate solution and the copper metal in the copper sulfate solution. Then connect the two metals to the voltmeter using wires. And finally connect the two beakers using a salt bridge.

The voltmeter will give a value, so an electricity is produced based on the chemical reactions produced inside the beakers.

First, the zinc metal is oxidized, from this oxidation reaction two electrons are produced they move into the wire and they are absorbed by the copper ions (Cu2+) in the second solution, so we can say that copper ions are reduced. Two half reaction occurs, one is the oxidation half reaction and the second is the reduction half reaction. The zinc metal is the anode, the oxidation always occurs on the anode, the copper metal is the cathode where the reduction reaction always occurs.

It is very important to know that electrons pass from the anode to the cathode in the electric wire.

Electrochemistry- Voltaic cell
Electrochemistry- Voltaic cell

What is the role of the salt bridge ?

A salt bridge is a laboratory device used to connect the oxidation and reduction half-cells of a voltaic cell. It provides a path for the migration of ions in order to maintain the neutrality of the solutions inside the two beakers.

Balancing the redox reaction using half reactions

Step 1 : Find the oxidation number of each atom in the two half reactions.

Electrochemistry- Voltaic cell

Step 2: Find the changes in oxidation number.

Electrochemistry- Voltaic cell

Step 3: Adjust coefficient so that the number of electrons lost in oxidation equal the number of electrons gained in reduction.

Step 4: Add the half reactions and cancel or reduce like terms on both sides of the equation to obtain the balanced REDOX reaction.

Electrochemistry- Voltaic cell

Examples of voltaic cell

There is so many examples of voltaic cells.

Electrochemistry- Voltaic cell
Electrochemistry- Voltaic cell