convert ppm to molarity

[johns]

Randy-

Can you help me with the equations to convert ppm to M.

I'm a little rusty (and lazy)! Do you know the calculations off hand and can you explain them.

I'm thinking about my questions about MgCl2 solutions. Kents is 70,000ppm (roughly). Trying to understand what molarity that is.

 

[Randy Holmes-Farley]

It is a little tricky without knowing the density of the fluid.

70,000 ppm = 70,00 mg/kg

magnesium weighs 24.3 grams per mole or 24.3 mg/mmole

so

70,000 mg/kg = [70,000 mg/kg ]/[24.3 g/mole] = 2.881 mole/kg = 2.9 mole/kg

molar is 1 mole/L

So if the fluid had a density of water (1 kg/L), then mole/kg = mole/L

but it is more dense, so that 2.9 mole in 1 kg is 2.9 mole in less than 1 L

Consequently, it is something above 2.9 molar.

Make sense?

 

[johns]

Randy-

makes sense. thank you

so now, how to find the density of ESV, Tech M, etc. (esp Tech M, for now)??

do you think it's reported somewhere? Actually I guess I could measure it myself on a balance if I just take a few mls and then get the weight. But if it was reported somewhere I'd just use that.

 

[Randy Holmes-Farley]

No, I expect it is not reported anywhere. Kent may not even know it. If I wanted the value for some reason, I'd measure it myself.

 

[Habib]

If it is 70,000 ppm Mg from MgCl2 then 1.13 - 1.14 is a reasonable value for the density.

However one should not to be too sure of that all manufacturers can calculate the concentration in the right way.

 

[Randy Holmes-Farley]

Thanks, Habib.

Presumably it has some sulfate in it as well, but perhaps not enough to change the densiy much.

 

[Habib]

<a href=showthread.php?s=&postid=6807225#post6807225 target=_blank>Originally posted</a> by Randy Holmes-Farley
Thanks, Habib.

Presumably it has some sulfate in it as well, but perhaps not enough to change the densiy much.

Actually I used measurement of a mix but at a somewhat lower concentration and did some extrapolation.

One of the reasons I did not state the temperature.

 

[Randy Holmes-Farley]

:thumbsup:

Thanks.