want someone to check if this is right,
Q: The concentration of lead in drinking water in a home was found to be 2.1x10-9 M. What is the concentration in ppm? ppb?
MM=207.2 g/mol. 1 ppm = 1 mg/L.
A: 2.1x10^-9 mol/L x 207.2 g/ 1 mol x 1000 mg / 1 g = 4.35x10^-4 ppm.
and that is equilvalent to 4.35x10^-7 ppb.
is this correct?
ppm = M * molar mass * 1,000
= 2.1*10^-9 * 207.2 * 10^3 = 435*10^-6
= 4.35 * 10^-4 ppm Agree with you
however would there not be more parts per billion than parts per million?
1 ppm = 10^3 ppb
so
4.35 * 10^-1 ppb
ahh yes I multiplied by 10^-3 instead lol thank you!
You are welcome :)
Yes, your calculations are correct. To convert the concentration of lead in drinking water from molarity (M) to parts per million (ppm) and parts per billion (ppb), you followed the correct steps.
First, you multiplied the given concentration of lead (2.1x10^-9 M) by the molar mass of lead (207.2 g/mol). This step allows you to convert from moles to grams.
Then, you multiplied the result by 1000 mg/g to convert from grams to milligrams.
Finally, you obtained the concentration in ppm by dividing by 1 mg/L (since 1 ppm is equivalent to 1 mg/L) and the concentration in ppb by an additional factor of 1000.
Therefore, the concentration of lead in drinking water is 4.35x10^-4 ppm and equivalently 4.35x10^-7 ppb.