I am currently working on calculations for my viscosity of liquids lab report.

I have calculated the viscosity of Methanol/Water mixtures of 0%, 20%, 40%, 60%, 80% 100% methanol/water.

Now, I am trying to calculate the Fluidity of the liquids using the following equation:

where x_A and x_B are the mole fractions of liquids A and B, and F_A and F_B are the fluidities of the pure liquids A and B. The fluidity of the mixture is, therefore, just the sum of the pure liquid fluidities, each weighted by its respective mole fraction.

I have no idea how to calculate the mole fractions for water and methanol just given the percentage of the solution and the individual fluidities.

For example, for my 20% methanol calculation the density of the mixture is 0.971g/mL

Would I find the moles by dividing the volume percentage of the solution by the density? but then how would I calculate the mole fraction?

Thank you in advance.

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