Question

I The amount of glucose to be dissolved in 500g of water so as to produce the same lowering in vapour pressure as that of 0.2 moral aqueous urea solution

Answer 1

For urea :m=0.2 and m=moles of urea(n)*1000/mass of solvent So, n*1000/mass of solvent=0.2 By this, relative lowering in vapour pressure =n*molar mass of solvent/mass of solvent=0.2*18/1000 =3.6/1000 .....(1) For glucose : relative lowering in vapour pressure =n*molar mass of solvent(water)/mass of water=mass of glucose (W)*18/180*500 = W/5000 ........(2)From 1and2, 3.6/1000=W/5000 So W=18g