## Convert ppmw to ppmv for liquids

## Convert ppmw to ppmv for liquids

(OP)

There is some disagreement in the office on how to convert ppmw to ppmv for a liquid system. The majority favors the following formula:

ppmv = ppmw * spgr (of the solution)

ppmv = ppmw * spgr (of the solution)

## RE: Convert ppmw to ppmv for liquids

I like to look at formulas with the worst case to see if they make sense. Suppose the stuff had infinite mass and tiny volume. It could be 99% of the mass and .001% volume, the formula creates that. And ther reverse no minimal mass huge volume.

## RE: Convert ppmw to ppmv for liquids

To put some numbers together for the sake of illustration, let's say we mix 100 liters of pure ethanol with 100 liters of pure water and ended up with 195 liters of ethanol-water mixture. What is the volume fraction of ethanol? Would it be 100/195? If you think "yes", then is the volume fraction of water also 100/195?

HTH,

Doug

## RE: Convert ppmw to ppmv for liquids

## RE: Convert ppmw to ppmv for liquids

You should note that ppmv and ppm on a mole basis are one and the same.

Doug