Ionic EquilibriumHard
Question
An acid type indicator, HIn differs in colour from its conjugate base (In–). The human eye is sensitive to colour differences only when the ratio [In–]/[HIn] is greater than 10 or smaller than 0.1. What should be the minimum change in the pH of the solution to observe a complete colour change (Ka = 1.0 × 10–5)?
Options
A.0.0
B.1.0
C.2.0
D.5.0
Solution
For complete colour change, PH should change from, $P^{H} \leq \left( P^{K_{a}} + \log\frac{1}{10} \right)\text{ to }P^{H} \geq \left( P^{K_{a}} + \log 10 \right)$and hence, minimum PH change should be of 2.0 units.
Create a free account to view solution
View Solution FreeMore Ionic Equilibrium Questions
Equimolar solutions of the following substances were prepared separately. Which one of these will record the highest pH ...The solubility product of Zn(OH)2 is 10–14 at 25oC. What would be the concentration Zn+2 ion in 0.1 M-NH4OH solution whi...Dissociation constants of acids HA and HB are 2.0 × 10−4 and 5 × 10−5, respectively. The [H+] in the resulting solution ...A pair of salts are given in a solution each in 0.1M concentration. Which solution has a higher pH ?...The pH of 0. 1 M solution of the following salts increases in the order :...