Topics: Carbon, Oxygen, Hydrocarbon, Chemical equilibrium, Chemical reaction, Chemistry / Pages: 48 (4560 words) / Published: Feb 7th, 2015
Environmental Chemistry

It often matters how much given atoms combine, in what arrangement, with what others, what impulse they receive, and what impart. The same ones make up earth, sky, sea, and streams; the same as the sun, the animals, grains and trees, but mingling and moving in every different ways.
- Lucretius (95-52 B.C.) in The Nature of

I. Physical Chemistry
Why is Physical Chemistry important in the study of Environmental
• Applied physical chemistry procedures is used to solve common environmental engineering problems

1. Stoichiometry
• It deals with numerical relationships between reactants and products in chemical reactions.
• Stoichiometric analysis can be used to determine the product yield for a given amount of reactant converted.

Example of Stochiometric Analysis
• Neutralization of hydrochloric acid with lime
2HCl + Ca(OH)2  CaCl2 + 2H2O
• Oxidation of acetic acid to carbon dioxide and water.
CH3COOH + 2O2  2CO2 + 2H2O

Engr. Yvonne Ligaya F. Musico


Example of Stochiometric Analysis
• Combustion of Methane
CH4 + 2O2  CO2 + 2H2O
• Oxidation of glucose
C6H12O6 + 6O2 6CO2 + 6H2O

Engr. Yvonne Ligaya F. Musico


Sample Problem 1
Freight train cars usually carry a maximum net weight of about 100,000 lbs. I f a train is carrying three cars of concentrated sulfuric acid (assume that it is 96% acid), how much lime [Ca(OH)2] would be required to neutralize the acid if it is spilled in a derailment or wreck? The neutralization reaction is
H2SO4 + Ca(OH)2 CaSO4

+ 2H2O

Sample Problem 2
What mass of carbon dioxide would be produced if 100 g of butane
(C4H10) is completely oxidized to carbon dioxide and water?

Theoretical Oxygen Demand
• It is an environmental engineering application of stoichiometry.
• The estimation of the amount of oxygen a known organic chemical will consume as it is converted to carbon dioxide and water.
• It is simply the amount of oxygen required to convert the material to carbon

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