The enthalpy of neutralization of weak monoprotic acid, HA in 1M solution with a strong base is `-55.95` KJ/mol if the unionised acid requires 1.4 KJ/mol heat for its complete ionization and enthalpy of neutralisation of the strong monobasic acid with a strong monoacidic base is `= -57.3` KJ/mol. What will be % ionization of weak acid in molar solution is

Options

A. `1%`
B. `3.57%`
C. `35.7%`
D. 0.1

Answer

B

Explanation

`HArarrH^(+)+A^(-),Delta_(r)H=1.4` kJ/mol
`DeltaH_("neutralization")=DeltaH_("ionization")+Delta_(r)H`
`(H^(+)+OH^(-)rarrH_(2)O)`
`-55.95=DeltaH_("ionization")-57.3`
`DeltaH_("ionization")" for 1 M HA = 1.35 kJ"//"mol"`
% heat utilized by 1 M acid for ionization
`=(1.35)/(1.4)xx100=96.43%`
so, acid is 100-96.43 = 3.57% ionized