Question

The self ionisation constant for $HCOOH$ is $10$ what percentage of $HCOOH$ are converted to $HCOO$ ion. The density of $HCOOH$ is $1.22g$ ${mL}^{-1}$.

Answer 1

R.E.F image

$HCOOH\rightleftharpoons HCO{O}^{⊝}+4^{\oplus }$

$\left[HCOOH\right]=\frac{n}{v}=\frac{mass}{mosot}\times \frac{1}{v}$

& $\frac{mass}{volume}=density$

$=\frac{1.22\times {10}^3}{46}$

$=26.52M$

$HCOOH\rightleftharpoons HCO{O}^{-}+H^{+}$

$\frac{x^2}{(1-x)}=k=10$

$x$ is small & it can be neglect

$x=\sqrt{10}$

$\%$ dissociation $=\frac{\left[HCO{O}^{-}\right]}{\left[HCOOH\right]}\times 100=\frac{\sqrt{10}}{26.52}\times 100=11.92\%$ Ans