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F 32 F CHEM 246 Spring 2016 Exam 1- Form A 6. Pure 353.8 26. Pure iodine (12) is

ID: 977015 • Letter: F

Question

F 32 F CHEM 246 Spring 2016 Exam 1- Form A 6. Pure 353.8 26. Pure iodine (12) is dissolved in carbon tetrachloride (CCla, 153.8 g/mol). If 105 g of iodine is CHEM 246 Spring 2016 dissolved in 325 g of CCla, please calculate the following a. What is the mole fraction of iodine? (4 points) 4137 2.S als .1637 moles sald molc s : ,11 mole> b. What is the vapor pressure of the solution at 65'C? (CCl& Pss0.6987 atm) |53.8 (4 points) 627 .1637 27. You are given a small bar of an unknown metal X. You find the density of the metal to be n Y Y rm diffraction experiment measures the edge of the face centered cubic cell

Explanation / Answer

a) No. of moles of CCl4 in 325 g = 325/ 153.8 = 2.11 mol

No of moles of I2 in 105 g of I2 =105 / 253.81 = 0.41 mol

Total no. of moles = 2.11+ .41 = 2.52 mol

Mole fraction of I2 = 0.41/ 2.52 = 0.16

b) The vapour pressure of a solution can be findout from the formula,

Psolvent = Posolvent x mol fraction of solvent

Substituting, Psolvent = 0.6987 atm x (2.11 / 2.52 )= 0.5850 atm