




		Dissolved Oxygen : Chemistry Theory

Titration Solution

With the final titration step, the focus is on the iodine equivalent rather than on the original molecular oxygen. Each drop of titrant added to the iodine indicates that a greater amount of dissolved oxygen was present in the original river water. The Sodium Thiosulfate Solution is titrated drop-by-drop, reducing the iodine back to its ionic form and changing the colour from yellow-brown to clear.