Bicarbonate indicator

Introduction

A bicarbonate Indicator is a pH indicator sensitive enough, to show a colour change as thje concetration of the gas carbon dioxide increases. Ther indicator is used in photosynthesis and respiration experiments to find out whether carbon dioxide is being liberated. The initial red colour changes to yellow as the pH becomes more acidic. Carbon dioxide, evne in the concentrations found in exhaled air, will dissolve in the indicator to form aweak carbonic acid, which will lower the pH and therefore give the characteristic colour change.

Composition

This solution is prepared in two separate solutions A and B respectively Solution A: - This solution sonsists of 0.02 gm of thymol blue, 0.01 gm cresol red and 2ml of ethanol Solution B: - This solution sonsists of 0.8 gm of sodium bicarbonate 7.48 gm of potassium chloride and 90 ml of water Working solution is preparedby mixing 1 ml of ( A+B) isn 100ml of distill water.