[sugarhillave]

in a soultion of sodium chloride in water, the vapor pressure is 19.6 torr at 25 degrees C.

i converted the pressure to 298.15 K and the temperature to .0258 atm.

i need to find out the mole fraction of NaCl, but i dont understand how to get either grams of moles.

[Demotivator]

Use Raoult's law
P(soution) = X(water) x P(water)
P(solution) = 19.6 torr
P(water) at 25C needs to be provided from some source.
Then calculate X(water) = mole fraction water.
From that calculate mole fractions NaCl. Remember, sum of all fractions = 1.