Reef Chemistry Question of the Day #234 Elements in Dissolved Organic Material

Randy Holmes-Farley

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Reef Chemistry Question of the Day #234

Which of the following elements would likely be most abundant in the dissolved organic material in a typical reef aquarium in terms of the numbers of atoms?

A. Hydrogen
B. Carbon
C. Oxygen
D. Nitrogen

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Randy Holmes-Farley

Randy Holmes-Farley

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b, the rest are gasses correct?

When they are pure elements they are gasses, but in this case, they are presumed to be part of organic molecules, which can be solids, liquids, or gases. :)
 

rushbattle

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I’m going with A, I think DOM is likely to be hydrocarbons, of which there are almost always more hydrogens than carbons.
 

NY_Caveman

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I am going to be different and say

D. Nitrogen

Probably way off but my amateur reasoning is food and waste.
 
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Randy Holmes-Farley

Randy Holmes-Farley

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And the answer is...

Which of the following elements would likely be most abundant in the dissolved organic material in a typical reef aquarium in terms of the numbers of atoms?

A. Hydrogen

Most organic molecules have more hydrogen in them than anything else. Often by a big margin. Note the question relates to numbers of the individual element, not mass. A few organics have more carbon than hydrogen, but not many. Only a very few have more oxygen than hydrogen.

By definition, an organic molecule contains carbon and hydrogen.

If you think of the typical organics that people are familiar with, these are some the element ratios

glucose C6H12O6
sucrose C12H22O11
ethanol C2H6O
Acetic acid (vinegar) C2H4O2
starch and cellulose C6H10O5
amino acid glycine C2H5NO2
amino acid aspartic acid C4H7NO4
amino acid tyrosine C9H11NO3
a typical unsaturated fat C55H98O
ATP (adenosine triphosphate) C10H16N5O13P3
Thymine (one of the 4 bases of DNA) C5H6N2O2
methane CH4

Happy Reefing. :)
 
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