3a) Calculate the mole fraction of B (Xb) in the vapor if a mixture of liquids i

Question

3a) Calculate the mole fraction of B (Xb) in the vapor if a mixture of liquids is 58%A and 42%B. The vapor pressure of pure A (PA) is 810 torr and the vapor pressure of pure B (PB°) is 759 torr Show caleulations and give answer to 2 decimal places. b) The mole fraction of B Xs) in the vapor of a mixture of A and B is 0.62 and the sum of the partial pressures of A and B is 780 torr. Calculate the mole fraction of B (Nb) in the liquid if the vapor pressure of pure B (PB°) is 727 torr. (Hint: Find Ps first) Show calculations and give answer to 2 decimal places (if not reporting as a percentage): 4) What is the character of the vapor after each condensation-vaporization cycle in a fractional distillation of a mixture? Explain the adiabatic process as it specifically pertains to a fractional distil!aion. 6) When carrying out a fractional distillation for the two components ofthe mixture you are distilling? b) what needs to be adjusted if the boiling point difference is smaller than above? 7) In vacuum distillation, how you do ensure that the liquid does not boil too suddenly upon reduction of pressure? 8) Since boiling stones cannot be used to control the bumping of liquids in vacuum distillation, hat is specifically done with glass wool (one of the implements used to other methods are used. W control bumping) when small quantities of material are being distilled via vacuum distillation? 9) In steam dstillation, which component according to Dalton's Law will have more molecules in the vapor phase?

Explanation / Answer

3 a) Mole fraction of liquid A in a mixture of A and B liquids (XA) = nA/(nA+nB), where n is the no. of moles

According to Raoult's law: Partial pressure of A in mixture(PA) = XA*PAo

According to Dalton's law of partial pressures: P = PA + PB

i.e. The mole fraction of A in the vapor phase (YA) = PA/P

By applying all the above formulae, PA = 0.58*810 torr = 469.8 torr

PB = 0.42*759 torr = 318.78 torr

Now, P = 469.8 + 318.78 = 788.58 torr

Therefore, YB = 318.78 torr/788.58 torr = 0.40

b) YB = 0.62

P = 780 torr

0.62 = PB/780

i.e. PB = 0.62*780 = 483.6 torr

Now, 483.6 torr = XB * 727 torr

i.e. XB = 483.6/727 = 0.66

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