Electrochemistry 1 PDF

**[Electrochemistry 1]** Electrochemistry may be divided into two areas; the use of an electric current to bring about chemical reactions, and the use of chemical reactions to produce an electric current. **[Electrolysis]** \*\*Definition: Electrolysis is the use of electricity to bring about a c...

**[Electrochemistry 1]** Electrochemistry may be divided into two areas; the use of an electric current to bring about chemical reactions, and the use of chemical reactions to produce an electric current. **[Electrolysis]** \*\*Definition: Electrolysis is the use of electricity to bring about a chemical reaction in an electrolyte i.e., a chemical reaction is produced when an electric current is passed through an electrolyte.\*\* \*\*Definition: An electrolyte is a compound which when molten or dissolved in water will conduct an electric current.\*\* Diagram of a battery in a beaker Description automatically generated(1) \- Two electrodes are used to make contact with the electrolyte. Electrodes are usually made or carbon or platinum since these are unreactive and do not react with the electrolyte.\ - Some electrodes do not react with the electrolyte into which they are dipping, these are called inert electrodes\ - Some electrodes react with the electrolyte, these are called active electrodes **[Purification of Copper]** \- The electrolysis of copper sulfate solution using copper electrodes is used to purify copper for the electronics industry\ - The impure copper is used as the positive electrode\ - A thin sheet of very pure copper is used as the negative electrode\ - As a current is passed through the cell, pure copper is plated onto the negative electrode\ - The impurities fall to the bottom of the cell **[Electroplating]** \*\*Definition: Electroplating is a process where electrolysis is used to put a layer of one metal on the surface of another.\*\* [To coat a spoon with silver\ ]- The object to be plated must be connected to the negative terminal of the battery\ - The electrolyte must be a salt of the metal that is being plates on to the object\ - The positive electrode must be made of the same metal as that being plated out The reactions that occurs are as follows:\ Negative electrode: Ag^+^ + e^-^ Ag↓\ Positive electrode: Ag Ag^=^ + e^-^ Electroplating is used to make an object appear more attractive. It is also used to protect an object against corrosion. Silver, chromium, zinc and tin are the metals most commonly electroplated on to cheaper metals. **[The Electrochemical Series]** \*\*Definition: The electrochemical series is a list of elements in order of their standard electrode potentials.\*\* (2) The elements at the top of the list lose electrons more easily than elements further down. Elements at the top are more reactive than elements further down. **[Exam Questions]** [2013 -- HL -- Section B -- Question 11] A An arrangement to demonstrate the electrolysis of molten lead bromide (PbBr~2~) using inert electrodes is shown in the diagram. The demonstration is carried out in a fume cupboard.\ (i) What is meant by electrolysis? Chemical reaction that occurs when electricity passes through an electrolyte\ (ii) Why must the lead bromide be molten? So that the ions are free to move\ (iii) Suggest a suitable material for the electrodes. Platinum\ (iv) Write balanced half equations for the reactions that occur at the electrodes during the electrolysis.\ Pb^2+^ + 2e^--^ → Pb\ 2Br-- → Br^2^ + 2e^--^\ (v) Name a metal, other than lead, that is extracted from one of its compounds by electrolysis. Sodium\ Name the compound that is electrolysed to produce this metal. Sodium chloride **[References]** 1. Classnotes.org.in 2. Onelearningsolution.blogspot.com