Why is a mole fraction independent of temperature?
1 Answer
Oct 10, 2017
Because mass is independent of temperature, and so is the number of particles (i.e. the mols).
Mole fraction is the ratio of the mols of one substance to the total mols:
#chi_i = n_i/(n_1 + n_2 + . . . + n_N) = 1/N sum_(i=1)^(N) n_i#
The mols of any substance can be related to its mass using its molar mass, i.e.
#cancel"mols" xx "g"/cancel"mol" = "g"#
And so, since the number of particles is independent of temperature, their mass is also independent of temperature. Volume, on the other hand, is not, and thus, neither is the density of a substance. That is why water density varies with temperature.
