Chemical list The gas concentration can be calculated using following equations: C(ng/sccm) = C(ppm) x K1C(ppm) = C(ng/sccm) x K2 where K1 = Molecular Weigh / 24.46K2 = 24.46 / Molecular Weight24.46 is the molar volume in liters @ 25°C, 760 mmHg