The mole fraction of urea in an aqueous urea solution containing 900   g of water is 0.05 . If the density of the solution is 1.2   g   c m - 3 , the molarity of urea solution is _______ (Given data: Molar masses of urea and water are 60   g   m o l - 1 and 18   g   m o l - 1 , respectively)
A. A
Mole fraction ⇒ 0.05 Number of moles of water ⇒ 900 18 = 50 ∴ n u r e a n u r e a + 50 = 0.05 n u r e a = 2.63 Mass of urea = W u r e a = 2.63 × 60 ⇒ 157.8   g Total mass of solution ⇒ 157.8 + 900 ⇒ 1057.8   g Volume of solution ⇒ 1057.8 1.2 m l ⇒ 881.5   m l Molarity ⇒ n o .   o f   m o l e s   o f   s o l u t i o n s v o l u m e   o f   s o l u t i o n   i n   L ⇒ 2.63 0.8815 ⇒ 2.98   M
Related: Chemistry — Some Basic Concepts of Chemistry · All PYQ Banks