QJEEM08Chfb2f: JEE Main 2008 Chemistry - Class 11 JEEM08Chfb2f Solution: Oxidising power of chlorine in aqueous solution can be…

Question

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Oxidising power of chlorine in aqueous solution can be determined by the parameters indicated below:

{1 \over 2}C{l_2}(g)

\overset{\frac{1}{2} Δ_{d i s s} H^{Θ}}{⟶}

Cl(g)

\overset{Δ_{e g} H^{Θ}}{⟶}

C{l^ - }(g)

\overset{Δ_{H y d} H^{Θ}}{⟶}

C{l^ - }(aq)

(Using the data,

{\Delta _{diss}}H_{C{l_2}}^\Theta

= 240 kJ/mol,

{\Delta _{eg}}H_{Cl}^\Theta

= -349 kJ/mol,

{\Delta _{hyd}}H_{C{l^ - }}^\Theta

= - 381 kJ/mol) will be :

Accepted Answer

The energy involved in the conversion of

{1 \over 2}C{{\rm}_2}\left( g \right)\,\,

to

{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} C{l^{ - 1}}\left( {aq} \right)

is given by

{\mkern 1mu} \Delta H = {1 \over 2}{\Delta _{diss}}H_{C{l_2}}^{\left( - \right)} + {\Delta _{eg}}H_{Cl}^{\left( - \right)} + {\Delta _{hy{\rm{I}}}}H_{Cl}^{\left( - \right)}

Substituting various values from given data, we get

\Delta H = \left( {{1 \over 2} \times 240} \right) + \left( { - 349} \right) + \left( { - 381} \right)kJ\,mo{l^{ - 1}}

= \left( {120 - 349 - 381} \right)kJmo{l^{ - 1}}

= - 610\,kJ\,mo{l^{ - 1}}

i.e., the correct answer is

(b)

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