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i had this answer on a chemistry exam, and answered 250mg/L. Does that sound correct?

Yes
For solutions
parts per hundred= %= g/100ml
so ppm= 10^-4* %= 10^-4 g/100mL= 10^-3 g/L= mg/L

2006-11-20 05:48:38 by Dan

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The new standard for arsenate in drinking water, mandated by the Safe Drinking Water Act, requires that by January, 2006, public water supplies must contain no greater than 10 parts per billion (ppb) arsenic.

Assuming that this arsenic is present as arsenate, AsO4 3-, what mass of sodium arsenate would be present in a 1.00 L sample of drinking water that just meets the standard?

10 parts by billion =10*10^-9=10^-8

so as a liter of water weighs 1kg=10^3g, the mass of AS must be lower than 10^3*10-8= 10^-5g
As O4 weighs 75+4*16= 139 (the charge has no effect on this calculus)

so the mass of AsO4 in one liter of watermust be lower than 139/75=1.85*10^-5g

2009-06-25 05:16:05 by help

The safe drinking water standard for arsenic (which is usually found as arsenate, AsO^4{3-) is 50 parts per billion (ppb) in most developing countries.

How many grams of sodium arsenate are in 55 gallons of water, if the concentration of arsenate is 50 ppb?
HINT:You will need molar mass of both AsO4(3-) and Na3AsO4? . First, 50 ppb AsO4(3-) of (let's say) 10^9 g of water yields 50 g of AsO4(3-) . Second, use the flow diagram (grams to moles; moles to moles, and moles to grams) (or dimensional analysis) to get to grams of Na3AsO4?, which should be a bit more than 50 g. Look carefully: the question in 4.116, part A, asks for the mass of Na3AsO4? .

In 1993, naturally occurring arsenic was discovered as a major contaminant in the drinking water across the country of Bangladesh. Approximately 12 million people in Bangladesh still drink water from wells that have higher concentrations of arsenic than the standard. Recently, a chemistry professor from George Mason University was awarded a $1 million Grainger Challenge Prize for Sustainability for his development of a simple, inexpensive system for filtering naturally occuring arsenic from drinking water. The system uses buckets of sand, cast iron, activated carbon, and wood chips for trapping arsenic-containing minerals. Assuming the efficiency of such a bucket system is 90% (meaning, 90% of the arsenic that comes in is retained in the bucket and 10% passes out of the bucket), how many times should water that is 5000 ppb in arsenic be passed through to meet the 50 ppb standard?

This is just a bunch of dimensional analysis:

55 gal * 3.79 L / 1 gal = 208.45 L

50 ppb = 50 g / 10^9 g = 50 ng/mL = 50 ug/L
remember -- 1mL = 1 gram of water

50 ug/L * 208.45 L = 10422.5 ug * 1g / 10^6 ug = 0.0104225 g AsO4

Molecular Mass of AsO4 = 138.92 g/mol
Molecular Mass of Na3AsO4 = 207.89 g/mol
0.0104225 g AsO4 * 1 mol AsO4 / 138.92 g AsO4 * 1 mol Na3AsO4 / 1 mol AsO4 * 207.89 g Na3AsO4 / 1 mol Na3AsO4 = 0.0155 g Na3AsO4

2008-09-26 15:05:56 by icegrl31882

u should follow the rules of potable water
the ph should be nearing 7 i.e. neutral
it should contain definite contents of chloride n magnesium salts

2007-04-14 05:33:35 by ak

He has put into law more deregulation of water and air and something else, (cant remember what)He did this so it would have more then 60days to become effective so it wont get reversed, why did he do this? Is our air and water quality no longer important? Does he hope we will all die sooner? His friends will get richer? Are thye going to sell the air next?

I think he lives on another planet.

Have you heard about those UFOs sitings in Earth County, Texas. Well, the next county is Hills County and Bush's ranch is in Crawford, Texas just a few miles away.

And since we are not popular with him, maybe he wants to give us some cancers or other air or water borne sicknesses to get even.

2008-11-01 13:21:21 by who's sane