Chapter 17, Problem 17.27QP

Interpretation Introduction

Interpretation:

The reason for small amount of indicator is used in titration has to be discussed.

Concept introduction:

• Acid-base indicator contains weak acid or base. It causes to change the colour of solution with change in $\text{pH}$ at end point.
• In acid-base titration, indefinite concentration of acid or base is titrated against known solution with help of indicator to point out the equivalence point.  Then, the volume of unknown solution and known solution used to calculate the concentration of unknown solution.
• Titration is a process where a known concentrated solution is used for determining the concentration of an unknown solution. The known concentrated solution is called the titrant, while the unknown concentrated solution is called the analyte.
• The equivalence point is a point in a titration where the amount of standard solution added is sufficient to neutralize the unknown solution completely. At this point, the total number of moles of standard solution (titrant) is equal to the number of moles of an unknown solution (analyte).
• $\text{pH}$: The concentration of hydrogen ion is measured using $\text{pH}$ scale. The $\text{pH}$ of a solution is a figure that expresses the acidity or the alkalinity of a given solution.
• It is defined as the negative base-10 logarithm of the hydrogen or hydronium ion concentration.

  $\text{pH}\text{=}{\text{-log[H}}_{\text{3}}{\text{O}}^{\text{+}}\text{]}$

• If the value of $\text{pH}$ is less than $7$, then the solution is acidic whereas if the value of $\text{pH}$ is greater than $7$, then the solution is basic, if the value of $\text{pH}$ is equal to 7 is neutral.