20 QUESTIONS FOR FREEZING POINT EXP Calculate the molar mass of an unknown non-e

Question

20 QUESTIONS FOR FREEZING POINT EXP Calculate the molar mass of an unknown non-electrolyte from its effect on the boiling point of ethanol. 1. Mass of ethanol used Normal boiling point of ethanol K, for ethanol Mass of unknown used Boiling point of solution 100.0 g 78.500 °C 1.20 °C/m 12.6 g 78.955 °C 2. How many grams of ealcium nitrate should be used with 250.0 mL of water to male the freezing point of the solution -13.4 C? Is it possible to make this solution if the solubility of calcium nitrate is 1212 g per liter of water?

Explanation / Answer

I am solving the Q1 as per Chegg guidelines, post multiple question to get the remaining answers

Q1)

Elevation in boiling Point = Boiling Point of solution - Normal boiling point

=> 78.955 - 78.500

=> 0.455C

Elevation in boiling point = i * Kb * m

Since non-electrolyte (i) = 1, Kb = 1.20C

m = 0.455/1.20 = 0.3792m

molality = number of moles of solute/mass of solvent in Kg = 0.3792

number of moles of solute = 0.3792 * 0.1 = 0.03792 moles

Mass/molar mass = 0.03792

Molar mass = 12.6/0.03792 = 332.27 gm/mol

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