We follow the same exact step, we add up the atomic weights and we get 62 grams/mol. Finally, to find the moles, we take our amount in grams divided by our molecular formula and we get 115 divided by 62 equals 1.85 moles of ethylene glycol. Finally, we use our formula to find out vapor pressure of the water molecules in this system. We simply multiply the mole fraction of water times the vapor pressure of water in the initial system and that is 5.51 divided by the total number of moles. The mole fraction 5.56
plus 1.85 gives us some fraction. That fraction is multiplied by 500 and that gives us 375.17
mmhg and that's the bigger pressure of these water molecules.