Unit 6: Solubility and Redox Reactions

Section 4: Galvanic Cells

Introduction

Galvanic Cells

About Galvanic Cells

Using The Power

Introduction

Electrochemistry, is basically the use of electricity to carry on chemical reactions or the use chemical reactions to produce electricity. In the next few sections, we will discuss the specifics of electrochemistry.

Galvanic Cell

A galvanic cell is basically a chemical reaction that produces electricity. An example of a galvanic cell, is a battery. For example, every time you turn on a flashlight, the power is coming to the lightbulb from the battery (which is a chemical reaction producing electricity or otherwise called, a galvanic cell.)

About Galvanic Cells

A galvanic cell, is as stated before, a chemical reaction that produces electricity. But how does it all happen? Well, galvanic cells are oxidation-reduction reactions (redox reactions.) As the electrons move from one element to another, the movement of electrons (or electricity) can be used to power something (like a flashlight.)

Using The Power

How do we use the power created by the cells? Well, to harness the power, we must separate the reducing agent and oxidation agent (so we can control the reaction) because if we don’t, the reaction would be spontaneous and we could not control what is happening. We then connect the two substances together using a wire. Then we must finish the connection by connecting the two solutions together using a salt bridge. A salt bridge is a connection between the two liquids that allow ions to move freely between the two solutions and keep each solution neutral. A salt bridge can be:

1. A U-shaped tube filled with an electrolyte that is inverted and placed between the seperated solutions.
2. A porous disk connecting the two solutions.
3. A paper towel soaked in an NaCl solution with one end placed in each solution.

Batteries have positive and negative terminals, and batteries are a kind of galvanic cell, so galvanic cells must have positive and negative terminals. The positive electrode in the galvanic cell, where the oxidation takes place is called that anode. The anode is also the place where electrons are lost. The negative electrode in the galvanic cell, where the reduction takes place is called the cathode. The cathode is the place where the electrons are received.