Question

Equal moles of water and urea taken in a flask.....calculate mass percentage of water

Answer 1

molecular mass of urea=60 and molecular mass of water=18
let the no. of moles of both be 1 mole
thus the weight of urea in flask=60 while weight of water in flask=18
total weight in flask=60+18=78
mass percent of water= 100*mass of water/total weight in flask
=100*18/60=30%

hope this helps!

Answer 2

Let 1 mole each of water and urea be taken.
Then mass of 1 mol water(H2O)=18g
and mass of 1 mol urea(NH2CONH2)=60g
Now mass percentage of water=(mass of 1 mol water/total mass of solution) x100=(18/(18+60) x100=23.07%
and mass percentage of urea =100-23.07=76.93 %