Toxic chemicals in drinking water usually are reported and a safety level specified in units of parts per million (ppm) by mass. What is the molar concentration of arsenic in a water sample that has 1ppm arsenic (As)?
DrBob222
1 ppm = 1 mg/L and although that isn't by mass at 1 ppm by mass and by volume is essentially the same.
So you have 1 mg/L
Convert 1 mg to mols As.
* I got 1.33 x 10^4.
I didn't obtain that answer.
Convert mg to grams, then convert grams As/L to mols As/L and that is M. Does it sound reasonable to you that a small concentration (like 1 ppm) is more than 10,000 M. I don't think so.
To determine the molar concentration of arsenic in a water sample with 1 ppm of arsenic (As), we first need to convert 1 ppm to milligrams per liter (mg/L).
Given that 1 ppm is equivalent to 1 mg/L, we have:
1 ppm = 1 mg/L
Next, we need to convert the mass of arsenic (1 mg) to moles. To do this, we need to know the molar mass of arsenic. The molar mass of arsenic is approximately 74.92 g/mol.
To convert from milligrams to grams, we divide by 1000:
1 mg = 1 mg / 1000 = 0.001 g
Now, we can convert grams to moles using the molar mass:
0.001 g As * (1 mol As / 74.92 g As) = 1.334 × 10^-5 mol As
Therefore, the molar concentration of arsenic in the water sample is approximately 1.334 × 10^-5 mol/L or 13.34 μmol/L.
To find the molar concentration of arsenic (As) in a water sample with 1ppm arsenic, we need to convert the mass concentration of 1ppm to molar concentration.
First, we know that 1ppm is equivalent to 1 mg/L (milligram per liter), as mentioned in your question. While ppm is a unit by mass, in this case, we can treat it as being equivalent to volume.
To convert from mass concentration to molar concentration, we need to know the molar mass of arsenic. The molar mass of arsenic (As) is approximately 74.92 g/mol.
To convert 1 mg/L to mols As, we can use the following steps:
1. Start with 1 mg/L.
2. Convert mg to grams by dividing by 1000 (since there are 1000 mg in 1 gram): 1 mg/L = 0.001 g/L.
3. Convert grams to moles by dividing by the molar mass of arsenic (74.92 g/mol): 0.001 g/L ÷ 74.92 g/mol = 1.334 x 10^-5 mol/L.
Therefore, the molar concentration of arsenic in the water sample is approximately 1.334 x 10^-5 mol/L or 1.334 x 10^-5 M (molar).