Mass Fraction This topic contains 1 reply, has 2 voices, and was last updated by Surjeet Sankararaj 5 years, 4 months ago. Author Posts June 10, 2013 at 10:19 pm #2480 KingParticipant Points: 96 What is mass fraction? What does it mean? June 11, 2013 at 10:29 am #2486 Surjeet SankararajKeymaster Points: 631 Consider a mixture of gases. The mass of the mixture (mm) will be equal to the sum of masses of individual gases (Σmi). Mass fraction is the ratio of mass of an individual gas to the mass of the mixture. Mass Fraction = (Mass of an individual gas)/(Mass of the mixture) Author Posts Tagged: mass You must be logged in to reply to this topic.