EVERYDAY SCIENCE

Detailed explanation-1: -The pH scale is used to rank solutions in terms of how acidic or how basic they are. It indicates the concentration of hydrogen ions (H+) and hydroxide ions (OH-) in a solution. These ion concentrations are equal in pure water, which has a pH of 7.

Detailed explanation-2: -As a result, pH is a measure of hydrogen ion activity. The activity coefficient is a function of the ion concentration and approaches 1 as the solution becomes increasingly dilute. Therefore, hydrogen ion concentration and hydrogen ion activity are nearly equal in very dilute samples.

Detailed explanation-3: -The pH value of a solution directly measures the concentration of hydrogen ions (H+) in the solution. Acids have a large H+ concentration, which translates to a small pH value. Bases have very little H+. Basic solutions have large pH values-greater than pH 7.

Detailed explanation-4: -The pH scale is commonly used to represent hydrogen ion activity. On the pH scale, pH values below 7 represent acidic solutions (hydrogen ion activity greater than hydroxide ion activity) while values above 7 represent basic solutions. At pH = 7, hydrogen ion and hydroxide ion activity are equal.