by Guest » Tue Jul 31, 2007 6:04 pm
If I assume:
1) You are talking ppm by weight
2) That ton is a METRIC ton (or tonne)
the answer is 22.5 g/Mg
A metric ton is 1000 kg or 10^6 g (1 Mg). Long and short tons are different.
Parts per million can be calculated based on weight, volume, mole fraction, etc. Without further information, the term is ambiguous and no one can be sure what is meant.