Question
At a giventemperature, you have a mixture of benzene (vapor pressure of purebenzene = 745 torr) and toluene (vapor pressure of pure toluene =290 torr). The mole fraction of benzene in the solution is0.590. Assuming ideal behavior, calculate the mole fractionof toluene in the vapor above the solution. 0.213 0.778 0.641 0.359 0.590 At a giventemperature, you have a mixture of benzene (vapor pressure of purebenzene = 745 torr) and toluene (vapor pressure of pure toluene =290 torr). The mole fraction of benzene in the solution is0.590. Assuming ideal behavior, calculate the mole fractionof toluene in the vapor above the solution.
0.213 0.778 0.641 0.359 0.590
Explanation / Answer
Given that Vapor pressure of pure benzene = 745 torr Mole fraction benzene = 0.59 Mole fraction of toluene = 0.41 Vapor pressure of pure toluene = 290 torr The partial pressure of benzene= Mole fraction benzene *Vapor pressure of purebenzene =0.59 * 745 torr = 439.55 torr The partial pressureof toluene = Molefraction toluene *Vapor pressure ofpure toluene =0.41 * 290 torr = 118.9 torr The molefractionof toluene in vapor = The partial pressureof toluene/ (The partial pressureof toluene +The partial pressure of benzene ) = 118.9 torr / (118.9 torr + 439.55 torr)
= 0.2129 Part II Moles of NaCl = mass / molar mass = 150.0 g / 58.453 g/mol =2.566 mol It is dissociated completely so total moles of soluteparticles in solution = 2* 2.566 mol = 5.1323 mol Moles of water = 1000g/18g/mol =55.56 mol Moles fraction of water = moles of water / totalmoles = 55.56 mol / (55.56mol + 5.1323mol) = 0.9154 The vapor pressure of solution =mole fraction of water * vapor pressure of pure water = 0.9154 * 23.8 torr
= 21.78 torr Part II Moles of NaCl = mass / molar mass = 150.0 g / 58.453 g/mol =2.566 mol It is dissociated completely so total moles of soluteparticles in solution = 2* 2.566 mol = 5.1323 mol Moles of water = 1000g/18g/mol =55.56 mol Moles fraction of water = moles of water / totalmoles = 55.56 mol / (55.56mol + 5.1323mol) = 0.9154 The vapor pressure of solution =mole fraction of water * vapor pressure of pure water = 0.9154 * 23.8 torr
= 21.78 torr