Electrolysis
Electrolysis is the process by which ionic substances are decomposed (broken down) into simpler substances when an electric current is passed through them.
Here is what happens during electrolysis:
- Positively charged ions move to the negative electrode during electrolysis. They receive electrons and are reduced.
- Negatively charged ions move to the positive electrode during electrolysis. They lose electrons and are oxidised.
We have seen that electrical conduction in solids is associated with the drift
of free electrons in the solid. A similar mechanism may be used to account for the conduction of electricity in liquid metals. In other liquids electricity is conducted by the migration of positive and negative ions through the liquid.
When two terminals, or electrodes, are immersed in a liquid and a source of emf is connected to them, there will be a current through the liquid. Those solutions are called electrolytes.
Electrolyte is a substance that conducts electric current as a result of a dissociation into positively and negatively charged particles called ions. The most familiar electrolytes are acids, bases, and salts, which ionize when dissolved in such solvents as water or alcohol.
Conductivity of Liquids
Good Conductors
- Materials through which electric current can pass through easily are called conductors of electricity. Electrical conductivity is a measure of the ability of a substance to allow the flow of an electric current. Among solids metals and graphite are good conductors of electricity which have high electrical conductivity. Some liquids are also good conductors.
- Solutions of most acids, bases and salts dissolved in water are good conductors of electricity. Electrical conductivity of liquids can be tested by a simple activity of taking a liquid, like lemon juice, in a container, inserting electrodes in it, connecting the two electrodes to the terminals of a battery with a bulb (LED) between them. The bulb glows, indicating that lemon juice is a conductor of electricity. Several liquids can be checked for electrical conductivity in the same way.
Summary
Made by:
- Marija Trajkovska
- Melanija Kraljevska
- Antonio Tashkovski
- When electricity is passed through a conducting solution, the molecules of the solution dissociate into ions.
- Ions are atoms or group of atoms with a positive or a negative charge. These ions cause electrical conduction through the liquid.
- A liquid that conducts electricity due to the presence of ions is called an electrolyte.
- Pure water or distilled water is a poor conductor of electricity. But the presence of even small amount of impurities makes water a good conductor. Hence water from taps, wells, ponds, rivers, seas, lakes, etc. conduct electricity as they contain inpurities. That is why we get electrical shock when we touch the conducting parts of electrical appliances with wet hands. Our dry hands also have sweat on them which conducts electricity. So we should never touch the conducting parts of electrical devices.
Whenever an electrolyte like metal sulfate is diluted in water, its molecules split into positive and negative ions. The positive ions or metal ions move to the electrodes connected with negative terminal of the battery where these positive ions take electrons from it, become pure metal atom and get deposited on the electrode. Faraday’s laws of electrolysis combine two laws and these are:
Faraday’s First Law of Electrolysis
The mass of a substance altered at an electrode during electrolysis is directly proportional to the quantity of electricity transferred at that electrode.
M = k ∙ Q
Faraday's Second Law of Electrolysis
For a given quantity of electricity (electric charge), the mass of an elemental material altered at an electrode is directly proportional to the element's equivalent weight.
Electrical Conduction In Liquids