The enthalpies of neutralization of HCN and H | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(D) The enthalpy of neutralization of a weak acid with a strong base is given by $\Delta H_{neut} = -57.3 + \Delta H_{ion}$,where $\Delta H_{ion}$ is

Vedclass · Accepted Answer

$pK_a$ of $HCN$ is greater than $pK_a$ of $H_2S$

Vedclass · Answer

(D) The enthalpy of neutralization of a weak acid with a strong base is given by $\Delta H_{neut} = -57.3 + \Delta H_{ion}$,where $\Delta H_{ion}$ is the enthalpy of ionization of the weak acid.Since the enthalpy of neutralization is less exothermic for $HCN$ $(12.13 \ kJ \ equi^{-1})$ compared to $H_2S$ $(15.9 \ kJ \ equi^{-1})$,it implies that more energy is required to ionize $HCN$ than $H_2S$.This indicates that $HCN$ is a weaker acid than $H_2S$.Since $pK_a = -\log(K_a)$,a weaker acid has a smaller $K_a$ value and consequently a larger $pK_a$ value.Therefore,the $pK_a$ of $HCN$ is greater than the $pK_a$ of $H_2S$.

The enthalpies of neutralization of $HCN$ and $H_2S$ with a strong base are $12.13 \ kJ \ equi^{-1}$ and $15.9 \ kJ \ equi^{-1}$ respectively. Then:

Similar Questions

Which of the following is the strongest conjugate base?

$H^{+}$ is a

For the reaction $HSO_4^- + OH^- \to SO_4^{2-} + H_2O$,which statement is correct regarding the conjugate acid-base pair?

Which of the following oxides will not give $OH^{-}$ ions in aqueous solution?

Complete the following Acid-Base reactions and identify each reactant as an Acid or a Base:
$(i)$ $CH_3NH_2 + H_2O$
$(ii)$ $CO_2 + H_2O$
$(iii)$ $H_2PO_4^- + CO_3^{2-}$
$(iv)$ $NH_2NH_2 + H_2O$
$(v)$ $C_6H_6 + NO_2^+$
$(vi)$ $C_6H_6 + NH_2^-$

Vedclass Test Series

Exam Paper Generator

Online Exam Module