Question

G potassium hydrogen phthalate (KHP) concentrations can be determined through titrating samples of KHP (a monoprotic acid) with bases such as NaOH in the presence of an indicator such as phenolphthalein. The indicator is colorless in an acidic solution and turns pink in an alkaline solution. Thus, we can establish an equilibrium for the phenolphthalein with the following reaction.

A) Discuss the principles of titration with KHP.
B) Explain the role of phenolphthalein as an indicator.
C) Describe the color changes during the titration.
D) Provide the chemical equation for the equilibrium involving phenolphthalein.

Answer 1

Potassium hydrogen phthalate (KHP) titration involves using phenolphthalein as an indicator to signify the neutralization point where the solution turns from colorless to pink,

Step-by-step explanation:

The principles of titration with potassium hydrogen phthalate (KHP) involve a reaction wherein a base (commonly NaOH) is added to a KHP solution until all the acid has been neutralized. This point of neutralization, known as the equivalence point, is determined using an acid–base indicator such as phenolphthalein.

Phenolphthalein plays a crucial role by changing color at a specific pH range, indicating the end point of the titration. In the case of phenolphthalein, it turns from colorless in acidic solutions to pink in alkaline solutions.

The color change during the titration is gradual until the end point, where a sharp change to pink signifies the completion of the reaction.

The equilibrium involving phenolphthalein can be represented by the chemical equation: HIn(aq) → H+(aq) + In−(aq), where HIn is the protonated (acidic) form, which is colorless, and In− is the deprotonated (basic) form, showing a pink color.

indicating the end point of the titration. The equilibrium for phenolphthalein is represented by the chemical equation involving its protonated and deprotonated forms showing different colors.