Question

Calculate the osmotic pressure exerted by a solution prepared by dissolving $1.5$g of a polymer of molar mass $185000$ in $500$ml of water at ${37}^o$C.

[R$=0.0821$ $L.atm.K^{-1}.mo{l}^{-1}$]

Answer 1

Given that

Mass of polymer = 1.5 g

Molar mass of polymer = 185,000

Volume of water, V = 500 mL = 0.50 L (1 liter = 1000 ml )

Temperature, T = (37 + 273)K = 310 K (add 273 to convert in Kelvin )

Using formula :

Number of moles, n $=\frac{Mass}{MolarMass}=\frac{1.5}{185000}=8.1\times {10}^{-6}$

Osmotic pressure is given by

$\pi =\frac{n}{V}\times RT$

putting in the values we get

$\pi =\frac{8.1\times {10}^{-6}}{0.5}\times 0.0821\times 310$

$\pi =41.27\times {10}^{-5}atm$