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SWS3022 Exam 3 Study Guide | Questions And Answers Latest {} A+ Graded | 100% Verified
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SWS3022 Exam 3 Study Guide | Questions And Answers Latest {} A+ Graded | 100% Verified
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SWS3022 Exam 3 Study Guide | Questions And Answers Latest {2024- 2025} A+ Graded |100% Verified
Know the two principal chemical elements in organic chemical compounds - Carbon & Hydrogen (maybe
Oxygen)
Know the two properties that make certain types of organic chemicals highly water soluble. - Polarity &
Electrical Charge
Understand basically the impediments to water solubility for non-ionic hydrophobic organic compounds.
- a. Solubility: The ease with which substances dissolve in water; the degree to which organic
contaminants impact soil and water quality often is related to their water solubility.
b. Non-ionic, non-polar organic chemicals do not possess an electrical charge, nor are the polar. So they
don't share any compatibility with water. Example: Dioxin
Given the relative insolubility of hydrophobic organic compounds, in what type of substances are they
soluble and why? - a. These types of chemicals are compatible with carbon-based environments (similar
chemically). They are soluble in environments that are chemically similar to their chemical properties.
Carbon-based compounds dissolve more easily in carbon-based solvents.
Understand how hydrophobic organic chemicals interact with organic colloids in soils. - a. An organic
colloid has a dense carbon, non-polar uncharged center and carboxylic, phenolic, and enolic (charged,
polar) moleculres surrounding it. They provide an organic domain/matrix, in which they move into that
organic environment because it is much more compatible with them.
b. In regards to synthetic organics: chemicals interact with soil organic matter and slow or arrest their
movement.
i. The lower the water solubility, usually the stronger the interaction, the slower the chemical
movement.
What is partitioning? - When the chemical will distribute between the organic and aqueous phases.; The
organic colloid behaves like an organic solvent.
Understand the basic relationship between the water solubility of organic chemicals and the strength of
interaction with organic colloids. - Organic chemicals tend to partition into the organic
domain/sediments. Examples of this are pesticides, DDT, and Toxaphene. (Persistence).
, Understand basically how hydrophobic organic compounds accumulate in organisms. - a. These
chemicals are highly hydrophobic, so they don't like to be in aqueous environment; it will accumulate in
the fatty tissues of organisms. It will avoid blood.
b. The "affinity" for carbon-based environments can lead to bioaccumulation, particularly of poorly
water soluble organic contaminants.
c. Lipid Tissue in organisms is principally composed of carbon and hydrogen. Triglycerides are the most
common. They are the main ingredient of fatty, or adipose tissue, and are stored in fat droplets inside of
adipose cells.
d. Hydrophobic organic compounds "prefer" the environment of the lipid tissues (lipophilic).
e. Despite low levels of organic chemicals in water due to their low water solubility, high amounts can
accumulate in the tissues of living organisms.
Understand basically how hydrophobic organic compounds accumulate in surface soils and aquatic
systems allowing them to persist in the environment. - a. Move out of aqueous phases and into that
organic colloids/soils. Why we still have issues with DDT today.
b. Soils as well as sediments in lakes and rivers often accumulate organic matter.
c. Hydrophobic organics become stored in these organic domains that naturally occur in aquatic and
terrestrial systems. This protects them from degradation and increases their lifetime in the
environment.
d. Most synthetic organic chemicals, particularly those like PCBs and DDT are very persistent in the
environment. They remain for decades.
Know what an octanol-water partitioning coefficient is, how it is determined, and what high or low
numbers indicate with respect to the ability of organic chemicals to bioaccumulate or persist in the
environment. - a. Kow= conc. of org. chem in octanol/ conc. of org. chem in water.
b. A high octanol-water partitioning coefficient generally corresponds to low water solubility and strong
attraction to carbon matrices. It indicateds a strong interaction with organic solvents and potentially,
soil O.M.
Know what an organic carbon partitioning coefficient (Koc) is, how it is calculated, and how it relates to
the movement of organic chemicals including pesticides through soils. - a. Koc= org chem in Soil carbon /
org chem in water(soil solution)
b. High Koc indicates stronger retention, slow movement in soils.
c. High Koc corresponds reasonably will to low water solubility and high Kow.
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