  A solution contains a 0.250 g of an unknown nonvolatile nonelectrolyte dissolved in 40.0g of CCl4 as the solvent. The boiling point of the solution was 0.357 ˚C higher than that of the pure solvent. Given Kb = 5.02˚C/m, determine the molar mass of the unknown substance.Molar mass unknown substance =? g/mol

Question

A solution contains a 0.250 g of an unknown nonvolatile nonelectrolyte dissolved in 40.0g of CCl4 as the solvent. The boiling point of the solution was 0.357 ˚C higher than that of the pure solvent. Given Kb = 5.02˚C/m, determine the molar mass of the unknown substance.

Molar mass unknown substance =? g/mol

Step 1

When a solute is added to a pure solvent , many changes occur in the properties of those solutions. These properties are called as colligative properties and they depend on the amount of the solute added not on their identities. One of them is the elevation in boiling point of the solution. When a solute or say a non-volatile solute is added to a pure solvent , its boiling point changes depending upon the amount of the solute that has been added. It is given by the relation :

Step 2

Firstly we need to find the molality of the solution which can be find as shown below

Step 3

Now we will substitute the value of m in the equation g...

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