Q. 10.78 - An Introduction to General, Organic, and Biological Chemistry

Question

Adding a few drops of a strong acid io water will lower the phi appreciably. However, adding the same number of drags to a buffer does not appreciably alter the ph. Why? (10.8)

Step-by-Step Solution

Answer

As a result, when the same amount of strong acid is added to a buffer, it is neutralized by the buffer's base.${\mathrm{H}}_3{\mathrm{O}}^{+}$. The ion concentration does not alter appreciably, hence the  $pH$of the solution remains almost constant.

Step 1:Introduction

The concentration of hydrogen ions used to determine a solution's acidity or alkalinity is defined as its pH . Acidic solutions have a pH value ranging from$0$ to $7$on the pH scale, while basic solutions have a pH value ranging from7   to $14$ on the pH scale.

Step 2:A strong acid

A strong acid dissociates completely in water to produce hydronium ions $\left({\mathrm{H}}_3{\mathrm{O}}^{+}\right)$. When a strong acid is added to water, the concentration of hydronium ions increases, lowering the of the solution (since is the negative logarithm of the hydronium ion concentration).

Step 3:A buffer neutralizes

 When a small amount of an acid or base is added to a buffer, it resists changes in the. A buffer neutralizes the added acid or base and keeps the solution nearly constant. As a result, a buffer functions as an acid or base shock absorber.

Step 4:A buffer is made up of a weak acid

A buffer is made up of a weak acid and its conjugate base. As a result, the additional acid, ${\mathrm{H}}_3{\mathrm{O}}^{+}$ions, reacts with the base, and the added base, ${\mathrm{OH}}^{-}$ions, reacts with the acid of the buffer system. A buffer is typically composed of equal amounts of a weak acid and its conjugate base, but it can also be composed of equal amounts of a weak base and its conjugate acid.

Step 5:Solution

As a result, when the same amount of strong acid is added to a buffer, it is neutralized by the buffer's base.. The ${\mathrm{H}}_3{\mathrm{O}}^{+}$ion concentration does not alter appreciably, hence the $\mathrm{pH}$ of the solution remains almost constant.