Q23 / 180 · COMEDK 2015 · Chemistry

Which of the following compounds have the same value of van't Hoff s factor $(i)$ as that of $\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}$ ?

  • Correct answer
    A
    $\mathrm{K}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]$
  • B
    $\mathrm{NaCl}$
  • C
    $\mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}$
  • D
    $\mathrm{Na}_{2} \mathrm{SO}_{4}$

Solution

The dissociation of compounds take place as follows: $\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3} \longrightarrow 2 \mathrm{Al}^{3+}+3 \mathrm{SO}_{4}^{2-}, i=5$ $\mathrm{~K}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right] \longrightarrow 4 \mathrm{~K}^{+}+\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{4-}, i=5$ $\mathrm{NaCl} \longrightarrow \mathrm{Na}^{+}+\mathrm{Cl}^{-}, i=2$ $\mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3} \longrightarrow \mathrm{Al}^{3+}+3 \mathrm{NO}_{3}^{-}, i=4$ $\mathrm{Na}_{2} \mathrm{SO}_{4} \longrightarrow 2 \mathrm{Na}^{+}+\mathrm{SO}_{4}^{2-}, i=3$

Hence, the correct answer is option: 'A'.

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