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Biphenyl, C12H10, is a nonvolatile solute that is soluble in benzene,C6H6. At 25

ID: 579708 • Letter: B

Question

Biphenyl, C12H10, is a nonvolatile solute that is soluble in benzene,C6H6. At 25°C, the vapor pressure of pure benzene is 100.84 torr. What is the vapor pressure of a solution made from dissolving 17.7 g of biphenyl in 32.0g of benzene?

2/14/2018 11:59 PM 43.3/100 Gras Print Calculatord Periodic Table income Sapling Learning Mapg Biphenyl, CzHo, is a nonvolatile, nonionizing solute that is soluble in benzene, CeHe. At 25 C, the vapor pressure of pure benzene is 100.84 torr. What is the vapor pressure of a solution made from dissolving 17.7 g of biphenyl in 32.0 g of benzene? Number 74.72 torr Explanatiorn -O Previous Give Up & View Solution Try Again O Next Ext Use the formula

Explanation / Answer


Molar mass of C6H6,
MM = 6*MM(C) + 6*MM(H)
= 6*12.01 + 6*1.008
= 78.108 g/mol


Molar mass of C12H10,
MM = 12*MM(C) + 10*MM(H)
= 12*12.01 + 10*1.008
= 154.2 g/mol

n(C6H6) = mass/molar mass
= 32.0/78.108
= 0.4097

n(C12H10) = mass/molar mass
= 17.7/154.2
= 0.1148

n(C6H6),n1 = 0.4097 mol
n(C12H10),n2 = 0.1148 mol

Total number of mol = n1+n2
= 0.4097 + 0.1148
= 0.5245 mol

use:
Mole fraction of C6H6
X(C6H6) = n1/total mol
= 0.4097/0.5245
= 0.7811

According to Raoult’s law:
P = Po*X(solvent)
p = 100.84*0.7811
p = 78.8 torr
Answer: 78.8 torr