(a) Define the following terms :

(i) Molarity

(ii) Molal elevation constant $(K_{b})$

(b) A solution containing 15 g urea (molar mass = $60 g m o l^{- 1}$ ) per litre of solution in water has the same osmotic pressure (isotonic) as a solution of glucose (molar mass = $180 g m o l^{- 1}$ ) in water. Calculate the mass of glucose present in one litre of its solution.

Open in App

Solution

(a) (i) Molarlty : It is defined as the number of moles of the solute present per litre of the solution.

(ii) Molal elevation constant $(K_{b})$ : It is defined as the elevation in boiling point when the molality of the solution is unity.

(b) Isotonic solutions have same molar concentration.

Molar conc. of urea ( $C_{1}) = \frac{15}{60} m o 1 L^{- 1}$

Molar conc. of glucose $(C_{2}) = \frac{W}{180} m o 1 L^{- 1}$

where W = amount of glucose $L^{- 1}$

$∴ \frac{15}{60} = \frac{W}{180}$

$W = \frac{15 \times 180}{60} = 45 g$

Suggest Corrections

Similar questions

Q. (a) Define the following terms:
(i) Molarity (ii) Molal elevation constant

(k_{b})

(b) A solution containing

15 g

urea (molar mass

= 60 g {m o l}^{- 1}

) per litre of solution in water has the same osmotic pressure (isotonic) as a solution of glucose (molar mass

= 190 g {m o l}^{- 1}

) in water. Calculate the mass of glucose present in one litre of its solution.

Q. A solution is prepared by dissolving

0.6 g

of urea (molar mass =

60 g m o l^{- 1}

) and

1.8 g

of glucose (molar mass =

180 g m o l^{- 1}

) in

100 m L

of water at

27^{0} C

. The osmotic pressure of the solution is :

(R = 0.08206 L a t m K^{- 1} m o l^{- 1})

Q. Mass of glucose in g must be present in 0.5 litre of a solution for its osmotic pressure be same as that of 8 g glucose in 1 litre is :

Q. (a) Define the following terms:
(i) Ideal solution (ii) Azeotrope (iii) Osmotic pressure
(b) A solution of glucose

(C_{6} H_{12} O_{6})

in water is labelled as

10

% by weight. What would be the molality of the solution?
(Molar mass of glucose

= 180 g / m o l

)

(a) A $10 %$ solution (by mass) of sucrose in water has a freezing point of 269.15 K. Calculate the freezing point of $10 %$ glucose in water if the freezing point of pure water is 273.15 K.
given:
(Molar mass of sucrose = 342 g $m o l^{- 1}$ )
(Molar mass of glucose = 180 g $m o l^{- 1}$ )
(b) Define the following terms:
(i) Molality (m)
(ii) Abnormal molar mass.

Join BYJU'S Learning Program