Water Hardness by Edta Titration

Experiment #3: Determination of Soda Ash (pH)

Kevin Carcano

Feb. 11th, 2014

Locker: 805B

Section: 203

Abstract:

This experiment used a sodium carbonate (Na2CO3) or “soda ash” sample to standardize a hydrochloric acid (HCl) solution. An unknown soda ash sample was titrated with the HCl solution using two indicator titrations and one potentiometric (pH meter) titration to measure the percentage of sodium carbonate present in it. An average of 28.11% +/- 0.2237% of sodium carbonate was present in the unknown sample.

Introduction and principles:

The purpose of this experiment is to determine the amount of soda ash present in an unknown sample. If successful titrations of sodium carbonate with hydrochloric acid are carried out, then the data gathered can be used to calculate the percentage of soda ash present in the unknown. Soda ash, which is the common name given to sodium carbonate is an important raw material in glass, chemicals, detergents, and other industrial products. It is produced naturally from the mineral trona and can also be manufactured by chemical processes, such as the Solvey Process. The largest natural soda ash deposit is in Green River, Wyoming. In 1998, soda ash was the 11th largest inorganic chemical produced in the country excluding petrochemical feed stocks1. The estimated 2012 distribution of soda ash by end use was glass, 48%; chemicals, 29%; soap and detergents, 8%; distributors, 6%; fuel gas desulfurization, 3%; miscellaneous uses, 3%; pulp and paper, 2%; and water treatment, 1%.2 Sodium carbonate can also be used to control the pH of pools and some foods. It its also used as a water softener and can be used as a cleaning agent when hard water has calcified on industrial equipment. The reaction between sodium carbonate and hydrochloric acid is,

Na2CO3 + 2HCl ---> 2NaCl + CO2 + H2O.

Experimental procedure:

A 500mL solution of ~0.1M HCl was prepared from a 12.M stock solution by adding 4.13mL of the stock...