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During electrolysis, substances like oxygen gas, chlorine gas, bromine etc. are liberated at the anode depending on the electrolytes used, while substances like hydrogen gas, copper, silver etc. are liberated or deposited at the cathode. The volume of gases liberated or mass of metals deposited depend on the amount of electricity that is passed, be it carried out on one or more electrolytes. These relationships were summarized by Michael Faraday into what are now known as the Laws of Electrolysis. Faraday's 1st Law of Electrolysis This law states that the mass of a substance deposited or liberated at the electrodes during electrolysis is directly proportional to the quantity of electricity passed through the electrolyte. Mathematically, this can be expressed as:                           m α Q ..................................(i) where, m = mass in grams (g); and Q = quantity of electricity in Coulombs (C) but,                          Q = I x t .............................

In our last post: Electrolysis of Some Typical Electrolytes (Part I) , we studied the electrolysis of acidified water, dilute sodium chloride and brine under different conditions. Here, we will be looking at the electrolysis of copper (II) tetraoxosulphate (VI), CuSO4, solution. In solution, copper (II) tetraoxosulphate (VI) undergoes complete ionization to form copper (II) ions, Cu2+, and tetraoxosulphate (VI) ions, SO4--, according to the equation:                                          CuSO4(aq) ----> Cu2+(aq) + SO4--(aq) .....................(i) Note that the two minus signs attached to the SO4 stand for 2- Electrolysis of Dilute Copper (II) tetraoxosulphate (VI) Using Inert (Platinum or Carbon) Electrodes The ions present in copper (II) tetraoxosulphate (VI) solution are Cu2+, SO4-- and H+, OH-; with the latter pair coming from the dissociation of water. Expectedly, the OH- and SO4-- ions migrate to the anode, while the H+ and Cu2+ ions migrate to the cathode. 

Recall that electrolytes are substances that conduct electricity in their aqueous or molten state, and get decomposed in the process. We are going to study the electrolysis of some electrolytes such as dilute tetraoxosulphate (VI) acid, dilute sodium chloride, concentrated sodium chloride, copper (II) tetraoxosulphate (VI) solution etc. Electrolysis of Acidified Water Using Platinum Electrodes The electrolysis of acidified water is carried out using the Hofmann voltameter . (Please click on the link or refer to your textbooks for a standard labelled diagram). Hofmann Voltameter Acidified water, which is simply dilute tetraoxosulphate (VI) acid, H2SO4, ionizes according to the equation:                                       H2SO4(aq) ----> 2H+(aq) + SO4--(aq) Meanwhile, the water molecules undergo partial dissociation to form H+ and OH-,                                      H2O(l) <----> H+(aq) + OH-(aq) Therefore, the acidified water contains three ion

Electrolysis is a word formed from two Latin words - 'electrum', which means electricity and 'lysis', which means to breakdown. Therefore, electrolysis is defined as the use electrical energy to breakdown a compound into its constituent elements. For instance, using electricity to decompose sodium chloride into sodium metal and chlorine gas, as depicted by their state symbols (s) and (g) in the equation below:                       2NaCl(aq) ----> 2Na(s) + Cl2(g) It is a redox process, and one needs a good understanding of redox reactions to understand it. (Kindly refer to our posts on Redox Reactions: Overview ,   Balancing Redox Equations and Oxidation Numbers ) Before we continue, it is imperative to understand the meanings of some terminologies in electrolysis. Definition of Terms Electrolyte This is a substance which conducts electricity in the aqueous or molten state and gets decomposed in the process. An aqueous solution is formed when a substanc