AP BIOLOGY

Detailed explanation-1: -pH is a measure of the hydrogen ion concentration in an aqueous solution. Essentially, pH measures acidity and alkalinity on a scale from 0.0 to 14.0. Pure water at room temperature (77° F) has a neutral pH, measuring 7.0.

Detailed explanation-2: -The pH of a solution is a measure of the molar concentration of hydrogen ions in the solution and as such is a measure of the acidity or basicity of the solution. The letters pH stand for “power of hydrogen” and numerical value for pH is just the negative of the power of 10 of the molar concentration of H+ ions.

Detailed explanation-3: -pH is really a measure of the relative amount of free hydrogen and hydroxyl ions in the water. Water that has more free hydrogen ions is acidic, whereas water that has more free hydroxyl ions is basic. Since pH can be affected by chemicals in the water, pH is an important indicator of water that is changing chemically.

Detailed explanation-4: -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.