Chemistry Report

Standardize a base of potassium manganate(VII) by an iron (II) salt (ammonium iron (II) sulphate) Introduction Oxidation modus operandis describe the numerate of electrons the mote depart gain or lose during a reaction. Each atom in an compare can be assigned an oxidation number according to certain rules. If the oxidation number of an atom increases as you go from the left side to the right side if an equation, oxidation has occurred (electrons have been at sea) if the oxidation number decreases, reduction has occurred (electrons have been gained). MnO4? + 8 H+ + 5e? Mn+? + 4 H2O (1) In the above reduction half-reaction, manganese has undergone a decrease in oxidation number from +7 to +2. In the following oxidation half-reaction, each iron atom has undergone an increase in oxidation number from +2 to +3. Fe+? Fe+? + e? (2) Oxidation must occur along with reduction. These reactions are called redox (reduction/oxidation ) reactions. The number of electrons lost and gained in the half reactions must be equal. The overall redox reaction becomes MnO4? + 5 Fe+? + 8H+ Mn+? + 5 Fe+? 4H2O (3) Potassium permanganate is widely use as an oxidizing agent in volumetric analysis. Since the MnO4 ion is a deep pink-violet colour and the Mn2+ ion is nearly colourless, the end point in titrations using KMnO4 can be interpreted as the first pink colour that persists in the upshot. In titration , permanganate solution is put in the burette and is run down to an acidified solution of reducing agent, e. g.. ammonium iron(II) sulphate solution. In this experiment, KMnO4 will be used to determine the percentage of Fe2+ in an unknown solid savor dissolved in water.The permanganate oxidation of Fe2+ to Fe3+ is carried taboo in an acidic solution to prevent the air oxidation of Fe2+. A potassium permanganate solution will be standardized by titrating it with a known mass of Mohrs salt, ferrous ammonium sulphate hexahydrate or Fe(NH4)2(SO4)26H2O. (Mohrs salt fulfils the requir ements of a primary standard. It is easily obtained in pure form, it is stable to oxidation when modify and is not hygroscopic. http//faculty. ccri. edu/eterezakis/1100%20Exp%205,%20Iron%20Analysis%20by%20Redox%20Titration%20_egt_. pdf http//www. mrteverett. om/Chemistry/labs/Chem%201A%20-%20Lab%20-%20Titration%20%28Redox%29. pdf Objectives To prepare and standardize a solution of an oxidizing agent,potassium manganate(VII) by titrating it with standard solution of a reducing agent,ammonium iron (II) sulphate. Then use the standardized to determine the concentration of a sample of unknown concentration. Materials Ammonium iron (II) sulphate crystals Potassium manganate (VII) solution Distilled water 1. 0M sulphuric acid apparatus Beakers 250cm? volumetric flask Conical flask Burette Pipette Electronic weighing machine Methods