Name: Mark L.
Why does the weight of sediment (dirt) mixed with water,
strained through various brands of paper towels, and oven dried for 20
minures (250F), not correlate with the remaining residue in the specimen
Does the dirt adhere to the water molecule, evaporate & then seem
Do you include the amount of soil stuck to the
paper towels in you calculations.
The heating of the sample certainly may cause
something in the sample to volatilize and
"disappear", leading to decreased sample weight.
David R. Cook
Environmental Research Division
Argonne National Laboratory
No, more likely you have just dissolved some salts or other soluble
solids. E.g., if you took table salt, stuck 1 gram in in a jar, mixed it
up in water, and dried it, you'd pretty much have 1 gram at the end. If
you took that same 1 g of salt, mixed it up in water, strained it through
paper towels, you'd be lucky to have anything left. Lots of other minerals
dissolve at least partially in water, so it's no surprise that you would
have less "dirt" left over after dissolving and straining it.
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Update: June 2012