Thermodynamics filled in class notes_Part_34

# Thermodynamics filled in class notes_Part_34 - 3.1. SOME...

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Unformatted text preview: 3.1. SOME GENERAL ISSUES 75 The mixture itself has a mean molecular mass: M m n , (3.17) = N i =1 m i n , (3.18) = N summationdisplay i =1 n i M i n , (3.19) = N summationdisplay i =1 y i M i . (3.20) Example 3.1 Air is often modeled as a mixture in the following molar ratios: O 2 + 3 . 76 N 2 . (3.21) Find the mole fractions, the mass fractions, and the mean molecular mass of the mixture. Take O 2 to be species 1 and N 2 to be species 2. Consider the number of moles of O 2 to be n 1 = 1 kmole, (3.22) and N 2 to be n 2 = 3 . 76 kmole. (3.23) The molecular mass of O 2 is M 1 = 32 kg/kmole . The molecular mass of N 2 is M 2 = 28 kg/kmole . The total number of moles is n = 1 kmole + 3 . 76 kmole = 4 . 76 kmole. (3.24) So the mole fractions are y 1 = 1 kmole 4 . 76 kmole = . 2101 , (3.25) y 2 = 3 . 76 kmole 4 . 76 kmole = . 7899 . (3.26) Note that N summationdisplay i =1 y i = 1 . (3.27) That is to say y 1 + y 2 = 0 . 2101 + 0 . 7899 = 1 . Now for the masses, one has m 1 = n 1 M 1 = (1...
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## Thermodynamics filled in class notes_Part_34 - 3.1. SOME...

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