A) You want to prepare an aqueous solution of ethylene glycol, HOCH 2 CH 2 OH, i

Question

A) You want to prepare an aqueous solution of ethylene glycol, HOCH2CH2OH, in which the mole fraction of solute is 0.116. What mass of ethylene glycol, in grams, should you combine with 955 g of water?

B)     You want to prepare an aqueous solution of ethylene glycol, HOCH2CH2OH, in which the mole fraction of solute is 0.116. What is the molality of the solution? To prepare this solution, 6.95 mol of ethylene glycol and 955 g of water were taken.

C) The molality of the NaI solution is 0.1. Calculate weight percent and mole fraction for NaI.

Explanation / Answer

answer c

0.1 moles NaI in 1 Kg of water
moles water = 1000 g/ 18.02 g/mol=55.5
total moles = 0.1 + 55.5 = 55.6
mole fraction = 0.1 / 55.6 =0.00179

mass NaI = 0.1 mol x 149.8938 g/mol= 14.9 g
mass solution = 1000 g + 14,9 = 1014,9 g
% = 14.9 x 100 / 1014.9 = 1.46 %

answer A

Moles water = 955 g / 18 g/mol = 53.1
mole fraction solute = moles solute / moles water + moles solute
let x = moles solute

0.116 = x / 53.1+x

6.63 + 0.116 x = x

x = 7.94 moles HOCH2CH2OH
mass HOCH2CH2OH = 7.94 mol x 62 g/mol = 492.77 g

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