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
pH of water is 7.0 at 25oC. If water is heated to 70oC, the:...Which of the following solutions will have pH close to 1.0?...Solid BaF2 is added to a solution containing 0.1 mole of Na2C2O4 solution (1 L) until equilibrium is reached. If the Ksp...Strong acids are generally used as standard solution in acid-base titrations because:...What is the pH of 10−7 M-HCl solution at 25o C?...