CHEMICAL EFFECTS OF ELECTRIC CURRENT

Introduction

When electric current is passed through conducting liquids, then chemical changes take place. This is called chemical effects of electric current. So, it is important that we should know some new terms like, electrolyte, electrode and electrolytic cell.

TERMS RELATED TO CHEMICAL EFFECTS OF ELECTRIC CURRENT:

• Electrolyte:  It is a liquid that conducts is electricity, e.g. a solution of copper sulphate salt in water is an electrolyte. The electrolyte contains ions and the flow of these ions (+ve or –ve) conducts electricity.
• Electrode: It is a solid electrical conductor through which an electric current enters or leaves something like a dry cell or an electrolytic cell. In other words, the carbon rods whose metal caps are covered by copper wires and joined to a battery are known as electrode. Electrode are of two types: Cathode and Cathode is an electrode which is connected to the negative terminal of the battery gets negatively charged. Anode is an electrode that is connected to the positive terminal of the battery gets positively charged.
• Electrolytic Cell: It is an arrangement having two electrodes kept in a conducting liquid or electrolyte in a vessel, e.g if we keep two carbon electrodes in a baker containing acidified water, then it will be an electrolytic cell.
• Electrolysis: The chemical decomposition produced by passing an electric current through an electrolyte is called electrolysis, e.g. An acidified water decomposes into hydrogen and oxygen by passing an electric current over it ( chemical effects of electric current).
• Electroplating: It is one of the most common application of the chemical effects of electric current. The process of depositing a thin layer of desired metal object with the help of electric current is called electroplating. The objective of electroplating is to protect the metal objects from corrosion or rusting.

 

PROBLEMS RELATED TO CHEMICAL EFFECTS OF ELECTRIC CURRENT:

Qs 1: It is dangerous to touch an electric appliance with wet hands, explain why?

Ans1: Since, wet hand acts as good conductor. So, we feel electric shock  when we touch electrical appliance with wet hands. 

Qs2 : Explain, why is layer of zinc coated over iron?

Ans2 : Layer of zinc is coated over iron because zinc prevents it from rust and corrosion.

Qs3 : Mention any one important difference in the conduction of electricity by solids and liquid.

Ans3 : Since, no chemical changes take place when electricity is allowed to pass through the solids while in liquids chemical changes take place when electricity is pass through it..

Qs4 : During the electrolysis of water at which electrode hydrogen gas is evolved ?

Ans4   During the electrolysis of water, hydrogen gas is evolved at the cathode.

Qs5 : Give the name of these substances which when added to the liquids make them good conductors of electricity.

Ans5 : Acids, bases, salts are when added to the liquids then these become good conductors of electricity. 

Qs6: sometimes we see the liquid is conducting but the bulb may not glow, why?

Ans6 : The bulb does not glow because the current flowing through it is very weak.

Qs7 : Will the solution of sugar in distilled water conduct electricity? 

Ans7 : The sugar solution in distilled water will make it a good conductor of electricity and current can easily pass through it.

Qs8 (chemical effects of electric current): Mention three effects of electric current. 

             Ans8 (chemical effects of electric current):  

• Heating effects of electric current
• Magnetic effects of electric current
• Chemical effects of electric current

Qs9 Name the effect of current responsible for the glow of bulb in an electric circuit. 

Ans9 : Heating effect of electric current is responsible for the bulb to glow in an electric circuit. 

Qs10: When a compass needle is brought near a current carrying wire, then what happens? 

Ans10: When a compass needle is brought near a current carrying wire, then needles deflects. 

Qs11 : Mention whether the distilled water conducts the electricity or not. 

Ans11: The distilled water does not conduct electricity.

Qs12 : Since, when an electric current is passed through two solutions A and B, the bulb glows brightly for solution b and dimly for solution A. so, which of these two is a better conductor? 

Ans12 : Solution B is a better conductor. 

Qs13: Mention the name of three liquids which can conduct electricity? 

Ans13 : Name of the liquids are

• Tap water
• Lemon juice or citric acid
• Vinegar or acetic acid 

Qs14 : Explain, how can we check that liquids conduct electricity?

Ans14: We can use the device ELECTRIC TESTER for checking of conduction of electricity through the given liquids. 

Qs15 : Explain the magnetic effects of electric current?

Ans15 : The electric current produces the magnetic field under which a current carrying wire behaves like a magnet. 

Qs16 : A chemical compound is produced by the method of electrolysis. Give an example.

Ans16 : Solution of sodium hydroxide (NaOH) or caustic soa is produced by the electrolysis of an aqueous solution of sodium chloride (NaCl) .

Qs17 Mention the place where should we dispose the waste electrolytes in electroplating?

Ans17 We should dispose the waste electrolytes far away from residential area. 

Qs18 The fresh fruits and vegetables conduct electricity to some extent. Explain why? 

Ans18 : Fruits  and vegetables are able to conduct electricity to some extent due to the presence of various salt solution in vegetables and acid in fruits. 

Qs19: Which one is better conductor of electricity: sea water or  drinking water? 

Ans19 : sea water is better conductor than drinking water as sea water contains more salt which increases conductivity.

Qs20 Why is tin electroplated on iron to make cans used for storing  food?

Ans20 : Electroplating is done on the iron to prevent it from rust and corrosion and it is cheap.

Qs21 : Name some substances with example which make a liquid good conductor.

Ans21 substances making a liquid good conductor are:

• Acids (H₂SO₄ / HNO₃ / HCl)
• Bases {NaOH / NH₄OH / Ca (OH)₂}
• Salts ( NaCl /ZnCl₂ / (NH₄)₂SO₄) 

Qs22 : What is LED? 

Ans22 LED is a devic or bulb which glows even at low or small current.

 Qs23  : Which form of energy conversion takes place in electric cell? 

Ans23 : In an electric  dry cell or battery, electric energy comes from chemical energy. 

———————————————————o—————————————————————————