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ERIC Number: EJ913220
Record Type: Journal
Publication Date: 2010-Feb
Pages: 5
Abstractor: As Provided
Reference Count: 13
ISSN: ISSN-0021-9584
Unraveling the Role of Sulfur Compounds in Acid Rain Formation: Experiments on a Wetted Glass pH Electrode
Lopes, Fernando S.; Coelho, Lucia H. G.; Gutz, Ivano G. R.; Vitz, Ed
Journal of Chemical Education, v87 n2 p157-161 Feb 2010
Vast quantities, on the order of megatons, of pollutants are emitted monthly to the atmosphere both by natural and anthropogenic sources. The evaluation of rainwater composition has great importance in understanding the atmospheric chemical composition, as water drops scavenge particles and soluble atmospheric pollutants. Most students are aware that SO[subscript 2] is one of the pollutants related to the acidification of the atmosphere owing to its oxidation in the gas or liquid phase that produces sulfate and H[superscript +], but the situation is more complex in the presence of other common pollutants such as ammonia or formaldehyde. To give insight into the chemistry occurring in the gas and liquid phases, a demonstration is described where the pH of a "raindrop" is monitored during absorption of SO[subscript 2] followed by exposure to H[subscript 2]O[subscript 2], with or without previous contact with gaseous CH[subscript 2]O. The effect of the presence of alkalinizing substances such as NH[subscript 3] in the atmosphere is evaluated as well. The raindrop is simulated by the wet bulb of a combination glass electrode exposed to the gas phase. Measurements can be made with any pH meter, although data acquisition with a computer is advantageous to illustrate the kinetics of the processes, as shown in the article. (Contains 4 figures and 4 notes.)
Division of Chemical Education, Inc and ACS Publications Division of the American Chemical Society. 1155 Sixteenth Street NW, Washington, DC 20036. Tel: 800-227-5558; Tel: 202-872-4600; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Descriptive
Education Level: Higher Education
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A