Q.
Arrange the following solutions in increasing order of their osmotic pressures.
(i) $34.2 \,g /$ litre sucrose
(ii) $60\, g /$ litre of urea
(iii) $90 \,g /$ litre of glucose
(iv) $58.5\, g / litre$ of sodium chloride
Solutions
Solution:
Sucrose
Urea
Glucose
$NaCl$
Strength $(g \,L^{-1})$ :
$34.2$
$60$
$90$
$90$
Molarity :
$\frac{34.2}{342} = 0.1$
$\frac{60}{60} = 1$
$\frac{90}{180} = 0.5$
$\frac{58.5}{58.5} = 1$
$i$ :
$1$
$1$
$1$
$2$
We know, $\pi t = iCRT$
Thus, Osmotic pressure of these solutions will lie in following sequence :
| Sucrose | Urea | Glucose | $NaCl$ | |
|---|---|---|---|---|
| Strength $(g \,L^{-1})$ : | $34.2$ | $60$ | $90$ | $90$ |
| Molarity : | $\frac{34.2}{342} = 0.1$ | $\frac{60}{60} = 1$ | $\frac{90}{180} = 0.5$ | $\frac{58.5}{58.5} = 1$ |
| $i$ : | $1$ | $1$ | $1$ | $2$ |