Notes, Exercises, Videos, Tests and Things to Remember on Chemical Effect of Current
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There are various uses of electricity in our daily life. We use electricity to light our homes, heat our rooms, to electroplate metals and many more. While using electricity we are basically converting electrical energy to various forms according to our need. These conversions of energy can also be regarded as effect of electricity. There are various effects of current and we will talk about two of those in here.
When current passes through the metal it produces heating and lighting effect. But what happens when electricity is passed through a liquid. Depending on liquid the effect differs. There are liquids that can conduct electricity and there are some that cannot. Water in its pure state cannot conduct electricity but if we add either acid or base or salt to it, water can conduct electricity. We will learn two different chemical effect of current:
The process of electricity conduction in liquid is called electrolysis. The process of electrolysis is possible due to presence of ions in the liquid. If a liquid cannot disassociate into ions then it cannot conduct electricity. For the process of electrolysis, we have to have a source of electricity (batteries) two rods that can carry electricity (anode (rod connected to the positive terminal of the battery) and cathode (rod connected to the negative terminal of the battery)) and solution that can carry electricity.
For electrolysis of water we have to take a battery (as a source of current), two graphite rods (one as anode and another as cathode) and wire to connect to rods and battery. As we already know water in pure state is a non-conductor, so we add sulphuric acid in the water. Now we will have ions in the liquid to conduct electricity. Water will break down into hydrogen ion (H+) and hydroxyl ion (OH-) and sulphuric acid will also break into hydrogen ion (H+) and sulphate ion (SO2--). This electrolysis of water will give you hydrogen gas at the cathode and oxygen gas in the anode. (Remember the output of the electrolysis differs according to the choice of solute in the water. If you choose NaCl i.e. table salt then you will get hydrogen at cathode and chlorine gas at anode) hen electricity is passed the following reaction occurs:
2H+(aq) + 2e- → H2(g)
4OH-(aq) – 4e- → 4OH
4OH (aq) → 2H2O (l) + O2(g)
Points to remember while doing electrolysis of water:
The process of laminating one metal to the other using electricity is called electroplating.It is similar to the electrolysis process as it requires a liquid medium that conducts electricity and a source of electricity and two rods that can act as cathode and anode. But in the process of electrolysis we use metal from anode to plate into the metal in cathode. Here products at anode and cathode do not have any importance rather metal from anode gets thinner as it gets plated on the metal in cathode. We are going to discuss electroplating of copper on iron nail.
To start the process we need an iron nail and a copper rod. The electrolyte we are going to use is copper sulphate (CuSO4). Copper sulphate in water disassociates into copper ion (Cu++) and sulphate ion (SO4--). When current is passed through the setup then following reactions occur:
Cu+++ 2e-→ Cu (Electroplated into iron)
Cu → Cu+++ 2e-(This cupper ion goes into solution so amount of Cu is reduced)
Electroplating stops when all the metal from anode is plated to anode.
Points to remember while electroplating:
Ostered discovered that electric current flowing through a conductor produced a magnetic effect around it. Micheal Faraday discovered that it was possible to obtain electric current in a circuit from a magnetic field.
Magnetic lines of force start from N- pole To S-pole. Internally these magnetic lines of force move from S-pole to N-pole. Magnetic lines of force are always closed. Magnetic lines through a surface of magnetic lines of force passing the surface held perpendicular to these lines of force.
The process of breaking down of electrolyte with the help of electricity is called electrolysis. When electricity is passed through the solution of electrolyte, the chemical reaction takes place. This process of decomposing electrolyte into ions is called electrolysis.
The process of coating one type of metal on other with the help of electricity is called electroplating.
The three basic conditions necessary for electroplating are as follows: -
Any two uses of electrolysis are as follows: -
The copper ions (cu++) will be collected on pure copper plate and result in the increase in size when pure copper is kept instead of iron nail and we can obtain pure copper as the result of this process.
the copper anode can't be used in water electrolysis process because nascent oxygen formed during the process reacts with copper to form copper oxide due to which the amount of oxygen will be reduced. That is why, copper anode can't be used in water electrolysis.
Which of the following is a strong electrolyte?
Copper sulphate solution
The electrode, connected to the positive terminal of a battery, is called ______.
The electrode, connected to the negative terminal of a battery, is called ______.
Electrolysis of water produces ______.
oxygen in cathode
hydrogen in cathode
oxygen trioxide at anode
both gas at cathode
Which of these solvent must be used during copper plating?
Copper sulphate solution
Sodium Chloride solution
Iron sulphate solution
Sodiun Sulphate solution