EXP 3_SIC2004_NUR SYAZANA BT HUSSIEN_17110220.pdf -...

This preview shows page 1 - 4 out of 12 pages.

Analytical Chemistry 1 Lab Report Name: Nur Syazana binti Hussien Matric ID: 17110220/2 Experiment: 3 Instructor: Assoc. Prof. Dr. Nor Kartini Abu Bakar Date: 19/10/2020
Title: Spectrophotometric Determination of Manganese in Steel Objectives: 1. To determine the concentration of manganese in steel from calibration curve of working standard solution of MnO 4 using UV-Vis. 2. To determine the percentage of manganese in steel. Introduction: Solid state is made up of variety of elements such as carbon, silicon, sulphur, phosphorus and manganese. The physical properties of steel depend highly on the content of these elements. Thus, the quantitative analysis of these elements is of great practical importance to exactly know how much the amount if each element. However, in this experiment we are focusing on only one element which is manganese. Manganese is determined spectrophotometrically as the purple coloured permanganate ion, MnO 4 ¯.Spectrophotometry is a method to measure how much a chemical substance absorbs light by measuring the intensity of light as a beam of light passes through sample solution. The basic principle is that each compound absorbs or transmits light over a certain range of wavelength. This is commonly used and an accurate method of determining the low concentrations of manganese in steel. The steel is dissolved in nitric acid to give a solution of manganese (II) ions. The periodate ion, added as the potassium salt, KIO 4 , readily oxidizes manganese (II) to permanganate according to equation 1 shown below. 2 Mn 2+ 5 IO 4 - 3 H 2 O 2 MnO 4 - 5 IO 3 - 6 H 2 + ………………. (Eq 1) The calibration curve is determined by measuring the absorbance of a series of standardised permanganate solution prepared. The permanganate can be accurately standardised using a primary standard, sodium oxalate. The oxalate anion, C 2 O 4 reduce permanganate to manganese (II) in acid solution at 60-70 according to equation 2 shown below. 2 MnO 4 - + 5 C 2 O 4 - + 16 H + + 2 Mn 2+ + 10 CO 2 + 8 H 2 O …………. (Eq 2) The concentration manganese in steel is determined from the calibration curve plotted. Also, concentration of manganese can then be determined by measuring the