Ionic EquilibriumHard
Question
The dissociation constant of formic acid is 0.00024. The hydrogen ion concentration in 0.002 M-HCOOH solution is nearly
Options
A.6.93 × 10−4 M
B.4.8 × 10−7 M
C.5.8 × 10−4 M
D.1.4 × 10−4 M
Solution
$\alpha = \sqrt{\frac{K_{a}}{C}} = \sqrt{\frac{0.00024}{0.002}} = 0.346\text{ or 34.6\%}$
Hence, α cannot be neglected.
$K_{a} = \frac{\alpha^{2}.C}{1 - \alpha} \Rightarrow 0.00024 = \frac{\alpha^{2} \times 0.002}{1 - \alpha} \Rightarrow \alpha = 0.29 $$$\text{Now, }\left\lbrack H^{+} \right\rbrack = C\alpha = 0.002 \times 0.29 = 5.8 \times 10^{- 4}$$
Create a free account to view solution
View Solution FreeMore Ionic Equilibrium Questions
A salt of strong acid and a weak base is dissolved in water. Its hydrolysis in solution is...An aqueous solution of a metal bromide MBr2 (0.04 M) is saturated with H2S. What is the minimum pH at which MS will prec...For a sample of pure water,...How many moles of NaOH must be removed from one litre of aqueous solution to change its pH from 12 to 11 ?...What mass of NaOH should be dissolved in sufficient water to get 20 m3 of an aqueous solution of pH 7.3 at 25o C?...