Question

Oxidising power of chlorine in aqueous solution can be determined by the parameters indicated below
`(1)/(2)CL_(2)(g)overset((1)/(2)Delta_(diss)H^(Theta))(rarr)Cl(g)overset(DeltaH_(Eg)^(Theta))(rarr)`
`Cl^(-)(g)overset(Delta_(hyd)H^(Theta))(rarr)Cl^(-)(aq)`
The energy involved in the conversion of `(1)/(2)Cl_(2)(g)` to
`Cl^(-)(aq)`
(Using the data `Delta_(diss)H_(Cl_(2))^(Theta)=240KJ mol^(-1)`)
`Delta_(Eg)H_(Cl)^(Theta)=-349KJmol^(-1)` ,
`Delta_(Eg)H_(Cl)^(Theta)=-381KJmol^(-1)`) will be
A. `+152 kJ mol^(-1)`
B. `-610 kJ mol^(-1)`
C. `-850 kJ mol^(-1)`
D. `+120 kJ mol^(-1)`

Answer 1

Correct Answer - B
For the process, `(1)/(2)Cl_(2(g)) rarr Cl_((aq.))^(-), DeltaH = ?`
`Cl_(2(g)) rarr Cl_((g))^(-)`,
`DeltadissH_(Cl_(2))^(ɵ) = 240 kJ mol^(-1)`
`Cl_((g)) + e^(-) rarr Cl_((g))^(-)`,
`DeltaegH_(Cl)^(ɵ) = -349 kJ mol^(-1)`
`Cl_((g)) + aq. rarr Cl_(aq.)^(-)`,
`Cl_((g))^(-)+aq.toCl_((aq))^(-),`
`ul(Delta_(hyd.)H_(Cl^(-))^(ɵ)=-381 kJ mol^(-1))`
`DeltaH=(Delta_(diss)H_(Cl_(2))^(ɵ))/2+Delta_(eg)H_(Cl)^(ɵ)+Delta_(hyd)H_(Cl^(-))^(ɵ)`
`= (240)/(2) + (-349) + (-381)`
`= -610 kJ mol^(-1)`