For the self-ionisation (protonation) process liquid formic acid at `20^(@)`C.
`HCOOH+HCOOHto HCOOH_(2)^(+)+HCOO^(-)`
the equilibrium constant,
`K=([HCOOH_(2)^(+)][HCOO^(-)])/([HCOOH]^(2))=10^(-10)`
At `20^(@)`C, the density of liquid formic acid is 0.92 gm/mL.
The ionic prodcut of formic acid,`K=[HCOOH_(2)^(+)][HCOO^(-)]` is :