CHM 101 Experiment 7
Dissolved Oxygen Levels in Natural Waters
Objectives
➢ To learn the chemical reactions involved in fixing and analyzing water sample for
dissolved oxygen using Winkler method.
➢ To determine the
...
CHM 101 Experiment 7
Dissolved Oxygen Levels in Natural Waters
Objectives
➢ To learn the chemical reactions involved in fixing and analyzing water sample for
dissolved oxygen using Winkler method.
➢ To determine the dissolved oxygen concentration of a natural water sample.
Introduction
The aesthetic appearance of bodies of water such as the color, surface growth and odor
indicate an immediate perception of the quality of water. Other parameters give clear
description of the quality of a water sample such as: pH, dissolved oxygen, alkalinity and
hardness. Alkalinity and hardness levels are determined by titrimetric techniques.
The level of dissolved oxygen in a water sample is an important factor for the quality of
water. Dissolved oxygen refers to the level of free, non-compound oxygen
present in water. Oxygen can slowly diffuse into water from the
surrounding atmosphere. It is an important parameter in assessing water
quality because of its influence on the organisms living within a body of
water. The amount of dissolved oxygen is a measure of the biological
activity in which high oxygen concentrations indicate aerobic conditions:
clean, clear and unpolluted. However, low oxygen concentrations indicate
anaerobic conditions: high turbidity, foul odors and extensive plant
growth on the surface. It is used as an indicator of the health of a water
body. The solubility of free oxygen in water is inversely proportional to
temperature and directly proportional to pressure. As the temperature increases, the
amount of oxygen decreases, however as the pressure increase the dissolved oxygen
increases. Dissolved oxygen level is usually reported in milligrams per liter (mg/L) or ppm.
The modern method for dissolved oxyg
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