Question

What will be the mole fraction of urea in 8% w/w urea
(aqueous) solution ?
(A) 0.8746 (B) 0.1254 (C) 0.0254 (D) 0.9745​

Answer 1

option c is correct ,....

mole fraction of urea =mole of urea/mole of urea+mole of solvent . here 8%w/w means 8gm urea . 100gm solution then solvent (water) is 100-8=92 gm and then calculate mole . mole of urea=weight/molecular mass, n(urea)= 8/60,,, n(urea)= 0.134 , then for water is 92/18 , n(water)= 5.12 ,.... mole fraction of the urea=0.134/0.134+5.12 , .... mole fraction of urea is 0.0254