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Metal Ions / Metal Systems If a metal plate or rod is placed in a solution of its own salt, two processes - oxidation and reduction, take place simultaneously. The atoms from the metal's surface, lose electrons and go into solution as ions, as the electrons lost are left on the surface of the metal plate, thereby making it electrons surplus and negatively charged.                    M(s) ----> M+(aq) + e- Conversely, the metallic ions in the salt solution gain electrons from the surface of the metal plate and get deposited as metallic atoms. The electrons gained from the surface of the electrode renders it electron deficient and positively charged.                     M+(aq) + e- ----> M(s) Depending on the nature of the metal, a particular process will predominate. Hence, a potential difference, known as the electrode potential for the metal ions/metal system [M+(aq)/M(s)] is established between the electrode and the electrolyte. For instance, if a zinc electrode is

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