# Chemistry

posted by .

Concentration 15.8 mg/L
Final Volume 100.0 mL

What is the concentration of phosphate in the original lake water sample if the unknown lake water sample in the option has been diluted by taking 25.0 mL of lake water and diluting it to the indicated final volume?

â€¢Chemistry - DrBob222, Wednesday, December 5, 2012 at 9:45pm
I don't know what "in the option" means. Is that 15.8 mg/L the concn in the 100 mL? If so then
15.8 x 100/25 = ? mg/L in the lake.

â€¢Chemistry - Anon, Thursday, December 6, 2012 at 12:38am
Don't you have times 100/25 by 1000mL/1L to get it to mg/L?

• Chemistry -

I still don't know what "in the option" means; however, if the concn is 15.8 mg/L in the measured sample, then multiplying by any dilution factor leaves the concn in mg/L and you do not need to multiply by anything.

• Chemistry Need Some to Check -

But when you times (100mL/25mL) you get 4mL. Then you times 4mL times 15.8 mg/L and it doesn't cancel out the mL.

• Chemistry -

What in the world are you talking about?
15.8 mg/L x (100 mL/25 mL) = 15.8 mg/L x 4 = 63.2 mg/L. (100 mL/25 mL) is 100 mL DIVIDED by 25 mL and that is 4. The mL of 100 and the mL of 25 cancel to leave a pure number x 15.8 mg/L to leave units of mg/L).
The units are mg/L x (mL/mL) = mg/L.

• Chemistry -

Ok. I thought 100mL/25mL=4mL. Thanks

• Chemistry -

I finally caught on to what you're doing. Your error is you think (100 ml/4 ml) = 4 mL. It isn't. It is 4. The mL in the top cancels with the mL in the bottom to leave a unitless number of 4.00

## Similar Questions

1. ### Chemistry HELP!!

A 100.0mL sample of the lake water was treated with 1.0mL of 1M AgNO3. 71.7mg of silver (I) chloride was isolated.What is the concentration of chloride ions in the water sample?
2. ### chemistry

A small lake contains 0.0500 mi3 of water [H2O]. If the density of water is 1.000 g/mL, determine the volume (in gal) of water in the lake.
3. ### Chemistry

A geologist removes a sample of water from a lake in Nevada where the water level has been slowly dropping over time. The sample is found to be 0.02M in borax. The lake is circular in shape and is currently 500 meters in diameter and …
4. ### Chemistry

Concentration 15.8 mg/L Final Volume 100.0 mL What is the concentration of phosphate in the original lake water sample if the unknown lake water sample in the option has been diluted by taking 25.0 mL of lake water and diluting it …
5. ### Chemistry

Water treatment plans must reduce phosphate levels to 3.2 micromoles PO4^3-/L before the water is considered drinkable. If water from Lake A is determined to have a phosphate concentration of 0.419 mg PO4^3-/L, does it meet this allowable …
6. ### chemistry

what is the concentration of phosphate in the original lake water sample if the unknown lake water sample
7. ### Calculus - HELP URGENT PLEASE

Consider a lake of constant volume 12200 km^3, which at time t contains an amount y(t) tons of pollutant evenly distributed throughout the lake with a concentration y(t)/12200 tons/km^3. assume that fresh water enters the lake at a …
8. ### environmental engineering

A lake receives 8 m3/s of inflow containing 0.3 mol/m3 of a chemical. The chemical reacts with a first order rate constant of 0.01 h-1. The outflow from the lake is also 8 m3/s. Assume there was no chemical in the lake at the beginning …
9. ### science check

The lake water in a location in Florida has been found to contain high levels of fecal coliform. What are people in the location most likely to do?
10. ### chemistry

If a 11.5 cm3 sample of lake water is found to have 178.5 ng As, what is the concentration of arsenic in the sample in parts per billion (ppb), assuming that the density of the lake water is 1.00 g/cm3?

More Similar Questions

Post a New Question