how do I

[funnytroll]

convert ppm to mg/m squared? What is the equation?

Cheers

[ChuckFickens]

ppm =(Y mg/m3)(24.45)/(molecular weight)

or

http://www.bu.edu/ehs/ih/chemicalsafety/NIOSH_ ppm_calculator.html

And type it in

Yeah I cheated :)

[ChuckFickens]

opppp wrong way

Y mg/m3 = (X ppm)(molecular weight)/24.45

[gen2]

That linked page won't open for me but instinct tells me that a fixed formula like the one quoted will only be true for a single medium.

Are you talking aqueous solutions here? or gases? or alloys? or rocks etc? Surely there will be a different formula for each or at least one that takes into account the molecular weight and density of the surrounding medium.

[gen2]

This is what I get from the link given above:

Forbidden
You don't have permission to access /ehs/ih/chemicalsafety/NIOSH_ppm_calculator.html on this server.

[ChuckFickens]

It would also depend on temp and pressure as both would effect density's

it's not an entirely fixed formula as it does include molecular weight in it, but yes probably loads of other variables. could/would effect the outcome

[funnytroll]

its for like nox emmissions in power stations etc

[ChuckFickens]

try this,

Seems to be the same one on a different site

[ChuckFickens]

oppps

http://www.entechinst.com/calc.php

[gen2]

You are OK funnytroll, the formula given IS for gases.

The number 24.45 in the equations above is the volume (liters) of a mole (gram molecular weight) of a gas or vapour when the pressure is at 1 atmosphere (760 torr or 760 mm Hg) and at 25�C.

That number would have to be changed to allow you to apply the formula to liquids or solids.