Home
Class 12
CHEMISTRY
Two aqueous solution containing, respect...

Two aqueous solution containing, respectively, 7 g urea (molar mass = 60 g) and 42 g of substance `X` in `100 g` of water freeze at the same temperarture. Calculate the molecular weight of `X`.

Text Solution

Verified by Experts

The given values are:
`W_("urea")=7 g`
`W_(X) = 42 g`
`W_(A)=100 g`
Now using formula, `Mw_(B)=(K_(f)xxW_(B)xx1000)/(DeltaT_(f)xxW_(A))`
For urea, `Mw_(B)=(K_(f)xx7xx1000)/(DeltaT_(f)xx1000)` ….(i)
For `X Mw_(B)=(K_(f)xx42xx1000)/(DeltaT_(f)xx1000)` ….(ii)
Dividing Eq.(i) from (ii), we get
`(60/Mw'_(B))=7/42` or`Mw'_(B)=360`
`:.` Molecular weight of `X = 360 g mol^(-1)`
Promotional Banner

Similar Questions

Explore conceptually related problems

Calculate the molality of an aqueous solution containing 3.0g of urea (mol.mass=60) in 250g of water.

Six grams of urea ( molar mass = 60 ) are dissolved in 90 g of water. The relative lowering of vapour pressure is equal to

The molality of a solution containing 0.1 mol of a substance in 100g of water is :

A solution is prepared by adding 2 g of a substance A to 18 g of water. Calculate the mass percent of the solute.

An aqueous solution containing one gram of urea boils at 100.30^(@)C . The aqueous solution containing 3.0 g of glucose in the same volume will boil at

6 grams of a substance 'A' dissolved in 100 g of water freezes at - 0.93^(@)C . The molecular mass of 'A' is ( K_(f)=1.86 Km^(-1) ).

The osmotic pressure of a solution containing 5 g of substance (molar mass =100) in 308 m L of solution was found to be 4.0 atm at 300 K . Calculate the value of solution constant (R)

10g of an organic substance when dissolved in two litres of water gave an osmotic pressure of 0.59 atm, at 7^(@)C . Calculate the molecular weight of the substance.

The vapour pressure of a solution cont.aning 10 g of a non-electrolyte in 200 g of water at a particular temperature is 2985 Pa. The vapour pressure of pure water at that temperature is 3000 Pa. Calculate the molecular mass of the solute.

4.5g of urea (molar mass = 60g "mol"^(-1) ) are dissolved in water and solution is made to 100 ml in a volumetric flask. Calculate the molarity of solution.