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Question
How will you determine molar mass of solute from osmotic pressure?
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Solution
For very dilute solution, osmotic pressure is given by
πV = n2RT
where,
π = Osmotic pressure in atm.
V = Volume of a solution in dm3
n2 = Moles of non-volatile solute
R = Gas constant = 0.082L dm3 atm K−1mol−1
T = temperature in Kelvin
∴ `pi = (n_2RT)/V`
`pi = (W_2RT)/(M_2V) ...[because n_2 = W_2/M_2]`
∴ `M_2 = (W_2 R T)/(pi V)`
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