Chapter 2.2, Problem 3LO

Summary Introduction

To explain:

The structure of the pH scale and the importance of buffers to biological systems.

Introduction:

The pH scale is used to measure the alkalinity and the acidity of the solution. It ranges on a scale from 0-14. The pH of 7 is considered neutral, pH below 7 is considered acidic and pH above 7 is considered alkaline. The pH above 7 is considered alkaline due to the increase in the concentration of the hydroxide ions and pH below 7 is acidic due to the increase in the concentration of the hydrogen ions. The concentration of the hydrogen and hydroxide ions is maintained by the addition of buffers into the solution. The examples include carbonic acid, and acetic acid. The carbonic acid dissociates to form the hydrogen ions and the bicarbonate ions, acetic acid dissociated to form acetate ions and hydrogen ions and water consists of hydrogen and hydroxide ions. The examples of acidic solutions are lemon juice, vinegar, tomatoes and coffee and examples of alkaline solutions include milk of magnesia and ammonia.

Pictorial representation:

The structure of pH scale is well represented in Fig.1.

Fig.1: Structure of pH scale ranging from 0 to 14.