Education Journalist | Study Abroad Lead
Conduction of electricity in liquids takes place with the help of charges through dissolving of compounds in water. The bonds of chemical compounds break down into a number of atoms which carry a positive or a negative charge in water. Flow of the freely moving charges lead to the conduction of electricity.
| Table of Content |
Keyterms: Electricity, water, Chemical compounds, atoms, Ions, Alcohol, Oil, Liquid, Acetic acid, Vinegar, Electrode, Liquid
Electrolysis or Conduction of Electricity in Liquids
[Click Here for Sample Questions]
The conduction of liquids depends totally on the capability of liquids to form ions. Some liquids such as oil and alcohol do not form ions and do not conduct electricity as well. Vinegar is mostly water with a very small amount of acetic acid in it. The acetic acid separates into ions present in the water. So, its solution conducts electricity. Conduction of tap water completely depends on its hardness.
The phenomena of chemical decomposition of liquid or solution constituting ions when the electricity passed through it are called electrolysis in water. The compounds which break its chemical bond in the water are called Ionic compounds. If you are thinking of an example; Sodium Chloride is an excellent example of an ionic compound. Atoms carrying charges are known as Ions. Ions carrying positive charge are called cations and the ions carrying negative charge are called anions. Now if you mix Sodium Chloride in water, freely moving ions will form. Cations travel to a negative electrode to collect the electrons and Anions navigate to the positive electrode and donate its extra electrons.
Construct a circuit using two cells, an LED and two connecting wires. Immerse two of the free ends of wires inside a beaker which has water or any other liquid without ends of the wires being touched. If the LED glows it means that the liquid conducts electricity. If the LED does not glow then it means that the liquid does not conduct electricity.
If the brightness of the LED glow is very high, then those liquids are good conductors. If the brightness of the LED is low, it denotes that less current is going through those liquids and they are very poor conductors of electricity. If the LED does not glow at all, it denotes that such liquids are insulators.
Also Read:
Electrolysis in Water
[Click Here for Previous Year Questions]
Electrolysis is referred to as a procedure of decomposing the ionic compounds into their elements with direct electric current being passed through the compound in the form of a fluid. The anions are oxidized at the anode and the cations are reduced at the cathode. The main components that are required for conducting the electrolysis are an electrolyte, electrodes, and some form of external power source is also needed to conduct the electrolysis.
H2O = 2H+ + OH-
Electrolysis is usually done in a vessel named ‘electrolytic cell’ which contain two electrodes (cathode and anode) and they are connected to a source of direct current and an electrolyte which is a type of ionic compound undergoing decomposition, in either molten form or in a dissolves state in a suitable solvent.
Reduction of Cathode
[Click Here for Sample Questions]
In this situation the hydrogen ions move towards the cathode. These positive cations gain an electron from the cathode and get converted into stable hydrogen gas.
H2O = 2H+ + OH-
2 H+(aq)+ 2e- → H2(g)
Oxidation at Anode
[Click Here for Previous Year Questions]
In this situation the negative hydroxide anion moves towards the anode. This negative anion loses an excess electron to the electrode and gets converted into stable oxygen gas.
4 H2O → 4 OH-(aq) + 4 H+
4 OH- (aq) → O2 (g) + 2 H2O (l) + 4 e
Application of Electrolysis
[Click Here for Sample Questions]
- Electroplating: It is the process of coating metals with another metal in order to protect the metal from corrosion.
- Purification of Metal: Electrolysis is very important in purifying the impure copper.
Faraday’s Laws of Electrolysis
[Click Here for Previous Year Questions]
There are two faraday’s laws of electrolysis:
Faraday’s First Law: It states that the mass of a substance, M, of a substance liberated during electrolysis is strictly proportional to the quantity of electricity that has passed through the electrolyte.
Therefore:
M = Mass of a substance
Q = Quantity of electricity
M = zIt
Q = It
where z is constant of proportionality which is the electrochemical equivalent.
Faraday’s Second Law: It states that the masses of the different substance deposited or liberated by the same quantity of electricity are strictly proportional to the equivalent of the substance.
Also Read:
Things to Remember
- The atom that loses an electron (or electrons) has more protons than the electrons.
- The atom that gains the electron (or electrons) has more electrons than the protons.
- Under some conditions, an atom may lose one electron or more than one electron, which gets added to another atom.
Previous Year Questions
- The chemical equivalent of copper and zinc are 3232 and 108108 respectively. When copper and silver…? [JKCET 2005]
- Aluminium displaces hydrogen from dilute HCl whereas silver does not. The E.M.F. of a cell…? [KCET 2004]
- Standard free energies of formation (in kj/mol) at 298 K are -237.2, -394.4 and -8.2 for…?
- A device, in which electrical energy is converted into chemical energy, is called…? [KCET 1998]
- Net cell reaction of Pt|H2(640mm)|HCl|H2(510mm)|Pt…? [BITSAT 2019]
- For which one of these metals the change in oxidation state from +2 to +3 is easiest? [MU OET 2010]
- Standard electrode potential of three metals X,Y and Z are…? [NEET 2011]
- Which of the following expressions correctly represents the equivalent conductance…? [NEET 2010]
- Which among the following is correct for electrolysis of brine solution? [MHT CET 2019]
- A 100.0mL dilute solution of Ag+ is electrolysed for 15.0 minutes with a current of…? [NEET 2018]
- In producing chlorine through electrolysis 100W power at 125V is being consumed. How much…? [VITEEE 2011]
- A current of 2.0A passed for 5 hours through a molten metal salt deposits 22.2g of metal…? [VITEEE 2013]
- The number of electrons delivered at the cathode during electrolysis by a current of 1 ampere…? [NEET 2016]
- The number of Faradays(F) required to produce 20g of calcium from molten…? [NEET 2020]
- The pair of electrolytes that posses same value for the constant (A) in the Debye…? [KCET 2020]
Sample Questions
Ques 1. At what time must a current of 20A pass through a solution of zinc sulphate to deposit 3g of zinc? (2 marks)
Ans. If the electrochemical equivalent z = 0.0003387gc-1.
I = 20A
m = 3g
Z = 0.0003387
M = zit
t = M/ ZI
t = 3 / 0.0003387*20
t = 443s
Ques 2. Why does hydrogen always get attracted towards the cathode and oxygen at anode? (2 marks)
Ans. Hydrogen after electrolysis goes towards the cathode because of its positive character, it attracts towards the negative electrodes (cathode). As a result of having a negative character oxygen does the same with positive electrodes(anode).
Ques 3. What are the types of electrolysis? (1 mark)
Ans. There are two types of electrolysis: strong electrolysis and weak electrolysis
Ques 4. Does pure water conduct electricity? (1 mark)
Ans. No, pure water is known as an excellent insulator and does not conduct electricity. Pure water and water are different, hence it must not be confused.
Ques 5. Which metal never conducts electricity? (2 marks)
Ans. There is no metal that does not conduct electricity entirely, but there are some metals available that are less effective conductors than other metals. Metal atoms have electrons in their outer shells that are not tied to any particular atom and it can always flow freely within the metal when electricity is applied. Gold is referred to as the most effective conductor of electricity. Pure copper and pure silver comes after it. Carbonized steel, pure lead and stainless steel are considered as the worst conductors of electricity among all the metals. Covalent and ionic solids, where the free-flowing electrons found in metals are absent, are said to be the best insulators, or non-conductors.
Ques 6. Paheli had heard that rainwater is considered as good as distilled water. So, she collected some rainwater in a clean glass tumbler and tested it with the use of a tester. To her surprise she found that the needle of the compass showed deflection. What could be the reason for deflection? (2 marks)
Ans. The rain water is a conducting solution as it contains dissolved salts. There is an absence of dissolved salts in distilled water. Hence, rainwater allows the electricity to pass through it, while distilled water cannot.
Ques 7. If the ammeter did not show any flow of electric current initially, nut when a few drops of dil. sulphuric acid was added to the liquid Z, the ammeter shown deflection. Identify liquid Z. (1 mark)
(A) Pure water
(B) Vinegar
(C) Brine solution
(D) Honey
Ans. A. Pure Water
Ques 8. What is the advantage of using LED over bulb while testing the electrical conductivity of liquids? (2 marks)
Ans. When there is a flow of electric current through a bulb because of the heating effect of the current, the temperature of the filament of the bulb gets heated and starts to glow. Incase of liquids consisting of low electrical conductivity, a weak current flows through the circuit as a result of which the filament doesn't get heated properly. THus the bulb fails to glow. Hence LED is more useful than bulb because LED glows more when there is a flow of current in the circuit.
Ques 9. What is an electrolyte? (1 mark)
Ans. Any substance that helps in conducting electricity in liquid state or when immersed in water and breaks down chemically during this process is known as electrolyte.
Ques 10. Why is zinc electroplated on iron? (1 mark)
Ans. Zinc is electroplated on iron in order to protect it from rusting.
For Latest Updates on Upcoming Board Exams, Click Here:https://t.me/class_10_12_board_updates
Also check:
Comments