Experiment 7

QUANTITATIVE ANALYSIS OF SODA ASH BY DOUBLE INDICATOR TITRATION

A.G.R. SUAREZ

INSTITUTE OF BIOLOGY, COLLEGE OF SCIENCE

UNIVERSITY OF THE PHILIPPINES, DILIMAN, QUEZON CITY 1101, PHILIPPINES

DATE SUBMITTED: 30 APRIL 2012

DATE PERFORMED: 26 APRIL 2012

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ABSTRACT

Soda ash, the common name for sodium carbonate (Na2CO3), has significant economic importance because of its applications in manufacturing glass, chemicals, paper, detergents and many other products. In this experiment, the purity of soda ash was determined, using titration.

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INTRODUCTION

This experiment aims to determine the purity of soda ash (Na2CO3) and similar samples. Crude sodium carbonate, Na2CO3, is commonly called soda ash. It is frequently used as a commercial neutralizing agent.

Besides the carbonate small amounts of sodium hydroxide, NaOH, and sodium hydrogen carbonate, NaHCO3, may also be present. Titrating with standard acid, usually HCl, makes it possible to determine the total alkalinity of the soda ash.

It is common practice to report the total alkalinity as percent sodium carbonate or sodium oxide, Na2O. Since samples are frequently non-homogeneous, the method of aliquot portions is usually employed. Instead of weighing out three separate samples of soda ash, one accurately weighs out a larger amount. This is then transferred into a volumetric flask, dissolved in water and then diluted to an accurately known volume. From this solution are then taken samples or aliquots on which the titration is carried out.

RESULTS AND DISCUSSION

This experiment aims to determine the purity of soda ash (Na2CO3) and similar samples using the double-indicator titration. The experiment also aims to understand the concept of titrimetric methods which include a large and powerful group of quantitative procedures that are based on measuring the amount of reagent of known concentration that is consumed...