(D) $\Delta T_f = T_o - T_f = 5.3 - 4.47 = 0.83 \ K$ Molar mass of $C_6H_5CH_2COOH = 136 \ g/mol$ Molality $(m) = \frac{0.223 \ g}{136 \ g/mol} \times

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Phenylacetic acid forms a dimer in benzene.

(D) $\Delta T_f = T_o - T_f = 5.3 - 4.47 = 0.83 \ K$ Molar mass of $C_6H_5CH_2COOH = 136 \ g/mol$ Molality $(m) = \frac{0.223 \ g}{136 \ g/mol} \times \frac{1000}{4.49 \ g} = 0.365 \ mol/kg$ Using $\Delta T_f = i \times K_f \times m$: $i = \frac{\Delta T_f}{K_f \times m} = \frac{0.83}{5.12 \times 0.365} \approx 0.444$ Since $i \approx 0.5$,it indicates that the solute molecules associate to form a dimer in benzene.

Class 12 Chemistry Solutions Abnormal molecular mass

Medium

Pure benzene freezes at $5.3^oC$. $A$ solution of $0.223 \ g$ of $C_6H_5CH_2COOH$ in $4.49 \ g$ of benzene freezes at $4.47^oC$. Given $K_f = 5.12 \ K \ kg/mol$,what can be concluded from this?

A
Phenylacetic acid $(C_6H_5CH_2COOH)$ remains as a monomer in benzene.
B
Phenylacetic acid undergoes partial ionization in benzene.
C
Phenylacetic acid undergoes complete ionization in benzene.
D
Phenylacetic acid forms a dimer in benzene.

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Abnormal molecular mass

If a $0.02 \, M \, Pb(NO_3)_2$ solution is isotonic with a $0.05 \, M$ aqueous glucose solution,the degree of dissociation of $Pb(NO_3)_2$ will be ..........

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The experimentally determined molar mass of a non-volatile solute, $BaCl_2$, in water by Cottrell's method, is

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Acetic acid dissolved in benzene shows a molecular mass of

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Pure benzene freezes at $5.3\,^oC$. $A$ solution of $0.223\, g$ of phenylacetic acid $(C_6H_5CH_2COOH)$ in $4.4\, g$ of benzene $(K_f = 5.12\, K\, kg\, mol^{-1})$ freezes at $4.47\,^oC$. From this,it can be concluded that phenylacetic acid ........

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The observed and calculated molecular mass of silver nitrate $(AgNO_3)$ are $92.64$ and $170$ respectively. The degree of dissociation of silver nitrate is ........ $\%$.

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Pure benzene freezes at $5.3^oC$. $A$ solution of $0.223 \ g$ of $C_6H_5CH_2COOH$ in $4.49 \ g$ of benzene freezes at $4.47^oC$. Given $K_f = 5.12 \ K \ kg/mol$,what can be concluded from this?

Similar Questions

If a $0.02 \, M \, Pb(NO_3)_2$ solution is isotonic with a $0.05 \, M$ aqueous glucose solution,the degree of dissociation of $Pb(NO_3)_2$ will be ..........

The experimentally determined molar mass of a non-volatile solute, $BaCl_2$, in water by Cottrell's method, is

Acetic acid dissolved in benzene shows a molecular mass of

Pure benzene freezes at $5.3\,^oC$. $A$ solution of $0.223\, g$ of phenylacetic acid $(C_6H_5CH_2COOH)$ in $4.4\, g$ of benzene $(K_f = 5.12\, K\, kg\, mol^{-1})$ freezes at $4.47\,^oC$. From this,it can be concluded that phenylacetic acid ........

The observed and calculated molecular mass of silver nitrate $(AgNO_3)$ are $92.64$ and $170$ respectively. The degree of dissociation of silver nitrate is ........ $\%$.

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