Chapter 17, Problem 17.73QP

Interpretation Introduction

Interpretation:

From the two given titration curves, the curve that denotes the strong acid should be identified.

Concept introduction:

Strong Acids: Acids that dissociates into ions completely which results in easy donation of protons are considered as strong acids. Strong acid forms weaker conjugated base.

$\text{pH}$: 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.

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

Acid dissociation constant ${\text{K}}_{\text{a}}$ represents how strong the acid is in a solution. ${\text{pK}}_{\text{a}}$ is defined as negative logarithm of acid dissociation constant (${\text{K}}_{\text{a}}$).

  $p{K}_a=-\log K_a$

The strength of acid decreases as the value of $p{K}_a$ increases

$p{K}_a$ represents the chance of losing proton from a compound.

Henderson-Hasselbalch equation

$\text{pKa}\text{=}\text{pH}\text{+}\text{log}\frac{\left[\text{HA}\right]}{\left[{\text{A}}^{\text{-}}\right]}$

Henderson-Hasselbalch equation explains the relationship between $pH$ of solution and $p{K}_a$ of acid. For a dissociation of acid $\left(HA\right)$ in aqueous solution,

  $HA+H_{2}O\underset{}{\overset{}{\rightleftharpoons }}{H}_3{O}^{+}+A^{-}$

  $p{K}_a=pH+\log \frac{\left[HA\right]}{\left[A^{-}\right]}$

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).