Electrochemistry is a branch of chemistry that explores the relationship between electricity and chemical reactions. One of its fundamental processes is electrolysis, which involves the decomposition of an ionic compound using an electric current. This process has significant applications in various industries, including metal purification and electroplating.
Before we start, here is a periodic table for your reference.
Electrolysis
Electrolysis is a process to chemically break down a compound using electricity.
Molten and Aqueous ionic compounds can be chemically broken down by the electrolysis process.
Electrolysis is a redox reaction as it involves the loss and gain of electrons.
Components of an electrolytic cell
Electrolysis process
Selective discharging of ions
Unlike molten electrolysis, aqueous electrolytes consist of 2 components: ionic compound and water. These results in 4 types of ions in an aqueous electrolyte, cation and anion of ionic compound and hydrogen, H+ and hydroxide (OH–) ions from water.
ONLY ONE cation and anion each is preferentially discharged at the cathode and anode respectively.
Factors for selective discharge of ions:
The LESS REACTIVE THE METAL, THE HIGHER TENDENCY of its metal ion (cation) to be discharged.
Concentration of anion
The HGHER THE CONCENTRATION OF ANION in an electrolyte, the HIGHER TENDENCY for it to be discharged.
Electrolysis of molten electrolyte
A molten electrolyte consists of 1 cation and 1 anion ONLY. Hydrogen ions, H+ and Hydroxide ions, OH– are not present in a molten electrolyte.
Electrolysis of aqueous electrolyte
An aqueous electrolyte consists of multiple cations and anions. Hydrogen ions, H+ and hydroxide ions, OH– are present in an aqueous electrolyte. Only 1 cation and 1 anion are preferentially discharged.
Electrolysis using reactive electrodes
Reactive anode electrode is involved in the electrolysis process and dissolves into electrolyte to form a cation as oxidation take place. Only 1 cation and 1 anion are preferentially discharges.
Applications for electrolytic cell
Industrially, electrolysis is used for purification of metals, electroplating and extraction of a metal from its ore. An impure metal, containing impurities, can be purified to obtain its pure metal by electrolysis process.
Components of electrolytic setup:
Anode > Impure Metal
Cathode > Pure Metal
Electrolyte > Metals salt solution of the metal being purified
Electroplating
It is a process of depositing a layer of metal on an object by the electrolysis process. This improves the appearance of an object and reduces rate of rusting (iron metal) or corrosion (all other metals) of the base metal.
Pure metal anode dissolves into electrolyte as oxidation takes place due to the loss of electrons.
What is the difference between Electroplating and Galvanising?
Extraction of a metal from its ore
Metals found at the top of the reactivity series are extracted from their metal ore by electrolysis
Components of the electrolytic setup:
Anode > Inert electrode
Cathode > Inert electrode
Electrolyte > Molten metal oxide of metal being obtained
Molten metal oxide may have an addition of an impurity to lower the melting point of the molten metal oxide, resulting in a more cost-effective electrolysis process.
Now, let’s move onto simple cell otherwise known as electrochemical cell.
Components of a simple cell
A simple cell is a device which produces electrical energy due to electron transfer taking place in the cell.
Electrolysis Process
Electrical energy produced by a simple cell
The voltage, measured by a voltmeter in a simple cell, is proportional to the amount of the electrical energy produced by the cell.
The further the metal anode and metal cathode are from one another in the reactivity series, the greater the voltage produced and the greater the amount of electrical energy produced.
When metal anode and metal cathode consist of the same metal, there will be no voltage or electrical energy produced.
Hydrogen Fuel Cell
Electrolysis plays a crucial role in industrial applications, from refining metals to producing clean energy. Understanding the principles behind electrochemical reactions enables scientists and engineers to develop sustainable technologies for the future.
We hope you’ve gained valuable insights into electrochemistry!
We hope you’ve gained valuable insights into electrochemistry! Let’s do some practice, download our PDF containing questions and answers.
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