Dissolved oxygen, environmental chemistry

The traditional areas of wet chemistry came under very close scrutiny and it was felt that whilst the overall size of Part D could be justifiably reduced, the chapter on titrimetry required modification to include a section on titrations in non-aqueous solvents as these are of particular application to organic materials. It was also felt that environmentally important titrations such as those for dissolved oxygen and chemical oxygen demand should be introduced for the first time. By way of contrast to this we considered that gravimetry has greatly diminished in application and justified a substantial reduction in volume. This in no way undermines its importance in terms of teaching laboratory skills, but the original multitude of precipitations has been substantially pruned and experimental details abbreviated. 

Dolan, E. Zhang, Y. Klarup, D. G. The Distribution Coefficient of Atrazine with Illinois Soils A Laboratory Exercise in Environmental Chemistry, / Chem. Educ. 1998, 75, 1609-1610. Dorman, S. C. Using the Local Watershed as an Outdoor Laboratory A Campus-Community Partnership , 225th Am. Chem. Soc. National Meeting, New Orleans, LA, March 23-27, 2003. Chem. Ed. Division Paper 130. Favaretto, L. An Inexpensive Device for Collection of Samples of Water for Dissolved Oxygen Determination without Air Contact, J. Chem. Educ. 1990, 67, 509. 

One familiar application of Henry s law is in the carbonation of beverages. If the partial pressure of CO2 above a solution is increased, the amount dissolved in the solution increases proportionately. When the beverage can is opened, dissolved gas bubbles out of solution in response to the lower CO2 pressure outside. Henry s law is important in biology, where gases such as oxygen dissolve in blood and other bodily fluids, and in environmental chemistry, where volatile pollutants can move between bodies of water and the atmosphere. 

The measurement of dissolved oxygen levels in aqueous solutions is an important index in medicine, biochemistry, molecular biology, and environmental, sanitation and industrial chemistry. This paper reviews the development of oxygen electrodes which work well under a variety of conditions. 

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