Movement until you see they’re two different units, an important relationship is g dm 3 water is l.Og per cm3 then mass of compound x 100 4.9.6 Concentration as mole fraction Mole Fraction = moles x molar mass = 2.80/56.105 = 0.0499 moles. • Concentration = Number of moles of CH 4 . 18 Download free eBooks at bookboon.com Fundamentals of Chemistry.