Question

The enthalpies of neutralisation of a strong acid $HA$ and weak acid $HB$ by $NaOH$ are $-13.7$ and $-12.7$ $kcal/eq$. When one equivalent of $NaOH$ is added to a mixture containing $1$ equivalent of $HA$ and $HB$; the enthalpy change was $-13.5kcal$. In what ratio is the base distributed between $HA$ and $HB$?

Answer 1

Let $x$ equivalent of $HA$ and $y$ equivalent of $HB$ are taken in mixture
$x+y=1$....(1)
$x\times 13.7+y\times 12.7=13.5$.....(2)
Solving eq (1) and (2) we get
$x=0.8,y=0.2$
$x:y=4:1$