Chemical Effects of Electric Current

William Nicholson, a British chemist demonstrated that bubbles of oxygen and hydrogen are formed when the electrodes are submerged in water and current is passed through the water. He noticed that the hydrogen bubbles were formed at the electrode connected to the negative terminal while the oxygen bubbles were formed at the electrode connected to the positive terminal.

William Nicholson, a renowned English Chemist discovered the electrolysis of water.

William Nicholson discovered the electrolysis of water

When an electric current flows through a conducting solution, chemical reactions take place in the solution. This is called the chemical effect of electric current. Some of the chemical effects of electric current are as follows:

  • Gas Bubbles are formed at electrodes
  • Metals are deposited on electrodes
  • Change of colour of the solution.

Do liquids conduct electricity?

All liquids do not conduct electricity. Nevertheless, some liquids are good conductors of electricity while others are bad conductors of electricity. Water with dissolved salts and minerals is a good conductor of electricity while distilled water is a bad conductor of electricity.

Material under test Good/Bad Conductor
Lemon Juice Good Conductor
Vinegar Poor Conductor
Honey Poor Conductor
Mercury Good Conductor
Soda Compounds Good Conductor

What happens when an electric current passes through a conducting solution?

The passage of electric current through a conducting solution results in chemical reactions. As a result, bubbles of gas may be deposited on the electrodes. Deposits of metal may be seen on electrodes. Changes in the colour of solutions may occur. The reaction would depend on what solution and electrodes are used.

When electricity is passed through water mixed with different substances, the constituents break into negative and positive ions. These ions pass an electric current through them. The more the number of ions, the better the conductor of electricity it is.

Experiment to Demonstrate the Conduction of Electricity in Liquids

  • Construct a circuit with a cell, connecting wires and an LED.
  • Insert the free ends of the wire into a beaker of water without touching each other.
  • If the LED glows, then it is an indication that the liquid is a conductor of electricity and if it doesn’t glow then it is an indicates that the liquid doesn’t conduct electricity.
  • The liquid is a good conductor of electricity if the brightness of the LED is high.
  • Likewise, if the brightness of the LED bulb is low, then the liquid is a bad conductor of electricity.

Applications of Chemical Effects of Electric Current

Electroplating

Electroplating is a process where a layer of metal is deposited on another material with the help of electricity. Based on the application, the right electrodes and electrolytes must be chosen. For depositing gold over a material, then an electrolyte containing gold must be chosen. Out of the two electrodes, one electrode should be of gold and the other electrode needs to be a material on which gold is coated.

Electroplating of Copper on Brass

Electroplating of Copper on Brass

While coating copper over brass, you need copper electrode and a brass electrode and any solution that contains copper in it such as copper sulphate solution. The copper electrode is made anode and the brass electrode is made the cathode. When current is passed through the copper sulphate solution, it breaks down into ions. The copper ions with a positive charge get attracted to the brass electrode and the sulphur ions with a negative charge get attracted to copper electrode. The amount of time taken for the completion of the process depends upon the strength of the being passed through the circuit and the concentration of the solution.

Applications of Electroplating

  • Electroplating is used in imitation jewellery which is made by applying a layer of gold or silver.
  • Parts of a bicycle and motorbike are chrome plated through electroplating.
  • Tin cans are made by electroplating tin on iron.
  • Beams of bridges and electric poles are electroplated with zinc.
  • Anodizing and chrome plating prevent corrosion.

Extracting Metals from their Ores

Electroplating is used to extract metals from metal ores. When electricity is passed through metal ores, they get broken down into ionic lattice. This way the metals are extracted separately. Metals such as sodium, calcium, potassium, aluminium and magnesium are obtained from their ores using this method.

Purification of metals

Electrolysis is used in the purification of metals by extracting impurities from them. The impure metal is used as an anode in the process and is dissolved in the electrolyte solution. During the process, the metal ions are deposited on the cathode and a pure form of metal is obtained here. The impurities remain in the electrolyte solution. Metals such as zinc, copper, aluminium and copper are purified this way.

Production of Compounds

Electrolysis is helpful in producing some compounds such as sodium hypochlorite.

Decomposition of Compounds

Electrolysis is used to decompose a compound into its constituents. Water can be decomposed into hydrogen and oxygen through electrolysis.

Frequently Asked Questions on Chemical Effects of Electric Current

How can you make pure water conduct electricity?

By dissolving salts in pure water, you can make it conduct electricity

Why does a compass needle when dipped in saltwater deflect more than when dipped in drinking water?

The seawater contains a huge amount of salts in comparison to drinking water, hence the seawater is a better conductor of electricity and it produces a stronger magnetic field in the wire and hence deflects the compass needle more.

What is the difference between electrolysis and electroplating?

Electrolysis is a process, which uses a direct electrical current to break chemical compounds while Electroplating is a process that uses electrical current to reduce dissolved metal cations so that they form a coherent metal coating on an electrode.

Why do firemen shut off the main electrical supply for the area before they use the fire hose?

The water used in the water hoses is not pure water and is a good conductor of electricity. So, the firemen shut off the electric supply before spraying water to save themselves and other people from electrocution.

Is rainwater a distilled water and a bad conductor of electricity?

Rainwater is pure water which is an insulator but it gets mixed with air pollutants like sulphur dioxide and nitrogen oxides and forms acidic solution, which is a good conductor of electricity. So, the compass needle shows deflection.

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