Question

The boiling point of diethyl ether, CH3CH2OCH2CH3, is 34.500 °C at 1 atmosphere. Kb(diethyl ether) = 2.02 °C/m

In a laboratory experiment, students synthesized a new compound and found that when 11.20 grams of the compound were dissolved in 271.8 grams ofdiethyl ether, the solution began to boil at 34.593 °C. The compound was also found to be nonvolatile and a non-electrolyte.


What is the molecular weight they determined for this compound ?

Answer 1

895.8g/mol

Step-by-step explanation:

Hello, here the solution:

Consider the formula for the boiling-point elevation:

`T_(solution)-T_(solvent)=K_(boil)m_(solute)`

We solve for the molality of the solute:

`m_(solute)=(T_(solution)-T_(solvent))/( K_(boil))=(34.593C-34.5C)/(2.02C/m)\\m_(solute)=0.046mol_(solute)/kg_(solvent)`

By knowing the mass of the diethyl ether (271.8 g =0.2718kg) and that 11.20g of the solute were dissolved, the molecular mass is given by:

`M_(solute)=(11.20g_(solute))/(0.046(mol_(solute))/(kg_(solvent)) *0.2718kg_(solvent)) \\M_(solute)=895.8g/mol`

Best regards.