questions Flashcards
what is the value of [O2(aq)] for water saturated with a mixture of 50% O2, 50% N2 by volume at 25 degrees celcius and a total pressure of 1.00 atm?
what stabilizes colloids composed of bacteria cells in water?
hydrogen bonding between water molecules and amino, carboxyl, and -OH groups on the cell surface
a sediment sample was equilibrated with a solution of NH4+ ion, and the NH4+ was later displaced by Na+ for analysis. A total of 33.8 milliequivalents of NH4+ were bound to the sediment and later displaced by Na+. After drying, the sediment weighed 87.2g. What was its CEC in milliequivalents/100 g?
(33.8meq/87.2g)x100=38.8meq/100g
what is the meaning of zero point of charge as applied to colloids? is the surface of a colloidal particle totally without charged groups at the ZPC?
the ZPC is the pH at which the sum of negative charges equal the sum of positive charges so that, although there are still charged groups on the colloidal particle surface, the net charge is zero
in terms of their potential for reactions with species in solution, how might metal atoms, M, on the surface of a metal oxide, MO, be described?
it is used to flocculate colloids
e
a sample of water contaminated by the accidental discharge of a radionuclide used for medicinal purposes showed an activity of 12,436 counts per second at the time of sampling and 8,966 cps exactly 30 days later. What is the half-life of the radionuclide ?
a polluted water sample is suspected of being contaminated with one of the following: soap, ABS surfactant, or LAS surfactant. The sample has a very low BOD relative to its TOC. Which is the contaminant?
both soaps and LAS surfactants have relatively high BODs whereas ABS surfactant does not biodegrade well and is probably the contaminant
A-3
B-4
C-2
D-1
B
A-4
B-1
C-2
D-3
how does reverse osmosis differ from a simple sieve separation or ultrafiltration process?
reverse osmosis depends on the affinity of the membrane for water and its rejection of ions
