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Calculate the molecular weight of cellulose acetate if its 0.2% (wt./vol.) solution in acetone (sp.gr.0.8) shows an osmotic rise of 23.1 mm against pure acetone at 27^(@)C. |
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Answer» Solution :`0.2`per cent solution means `0.2g` of CELLULOSE acetate DISSOLVED in 100mL of solution. Osmotic PRESSURE `=2.31cm` of acetone `p=2.31xx(0.80)/(13.6)cmHg=0.136cmHg` `p=(0.136)/(76)atm.` `(1atm=76cmHg)` Suppose M is the MOLECULAR weight of cellulose acetate `n=(0.2)/(M)`, `V=100mL=0.1` litre, `R=0.082` lit. atm/K/mole and `T=273+27=300K` Now, `p=(n)/(V)RT` ..............(Eqn. 6) `:.(0.136)/(76)=(0.2//M)/(0.1)xx0.082xx300` `M=27500` |
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