Question

$ 50\,c{{m}^{3}} $ ethylene glycol is dissolved in 50g water. Freezing point of solution is $ -34{}^\circ C $ Assuming ideal behaviour than density of ethylene glycol is (for water, $ {{K}_{f}}=1.86\,K\,kg\,mo{{l}^{-1}} $ )

• A. $ 1.273\text{ }g/c{{m}^{3}} $
• B. $ 2.173\text{ }g/c{{m}^{3}} $
• C. $ 1.133\text{ }g/c{{m}^{3}} $
• D. $ 2.612\text{ }g/c{{m}^{3}} $

Answer 1

Answer: (C)

Volume of ethylene glycol $ =50\text{ }c{{m}^{3}} $ $ \therefore $ Mass of ethylene glycol $ (w)=50\times d $ And, $ W=50g $ $ \Delta T={{0}^{-}}(-34)=34 $ $ {{K}_{f}}=1.86K\,\log mo{{l}^{-1}} $ $ \therefore $ $ \Delta {{T}_{f}}=\frac{1000\times {{k}_{f}}\times w}{62\times 50} $ (Mol. mass of ethylene glycol= 62) or $ d=\frac{34\times 62\times 50}{1000\times 1.86\times 50} $ or $ d=1.33\,g/c{{m}^{3}} $