Question

mole fraction of urea in a solvent is 0.1 .if molarity of this solution is 10/9m then molar mass of solvent (in g/mol)​

Answer 1

Answer:

Molarity of urea = 1.25 M

Explanation:

mol fraction= mol of solute/( mol of solute + solvent )

0.1= mol of solute/( mol of solute + solvent )

If, mol of solute + solvent= 1

Molecular weight of urea = 60g/mol = 0.6 grams

0.1=moles of solute(urea) = 0.6 grams

0.9=moles of solvent(water) = 16.2 grams

mass of soln= 0.6 +16.2= 16.8 grams

Volume= Mass/ Density=1 16.8/1000d L

M= mol of urea/ litre of soln

M =0.1 ÷ 16.8/1000d

M = 1/10 x 1000d/ 16.8

M = 100d/16.8 = 125d/21 M

d=0.21 gm/mL, we can put this value in the above equation to get-

M of urea= 125 x 0.21/21=1.25 M