Question

1 molal aqueous solution of methanol is provided. The mole fraction of methanol in the solution is....

Answer 1

Answer: The mole fraction of methanol in the given aqueous solution is 0.0176 moles.

Explanation:

Molality = no. of moles of solute / Weight of solvent in Kg

Here, 1 molal aqueous solution of methanol indicates 1 mole of CH3OH dissolved in 1Kg or 1000g of water.

Moles of solute (CH3OH) = 1 mole

Moles of solvent (H2O) = 1000 / 18 moles ..........( As, 18g ---> 1mole,

                                          = 55.55 moles                   1000g ---> 1000/18 moles)

Now,

mole fraction of methanol, X (CH3OH) = n (CH3OH) / {n(CH3OH + n(H2O)}

                                                                      =      1 / ( 1 + 55.55)

                                                                      =       0.0176 moles