NCERT · Class 10 · Science · Acids, Bases and SaltsDescribe the properties of strong acids and bases, and explain the pH scale.

Properties of Strong Acids and Bases

Strong acids are substances that completely dissociate in water to produce hydrogen ions (H+). Examples include hydrochloric acid (HCl), sulfuric acid (H2SO4), and nitric acid (HNO3). They have a pH of less than 7 and are highly corrosive.

Strong bases, on the other hand, are substances that completely dissociate in water to produce hydroxide ions (OH-). Examples include sodium hydroxide (NaOH), potassium hydroxide (KOH), and calcium hydroxide (Ca(OH)2). They have a pH of more than 7 and are highly alkaline.

pH Scale

The pH scale is a measure of the concentration of hydrogen ions in a solution. It ranges from 0 to 14, with 7 being neutral. A pH of less than 7 is acidic, while a pH of more than 7 is basic.

The pH scale is logarithmic, meaning that each step up or down represents a tenfold change in the concentration of hydrogen ions. For example, a solution with a pH of 4 has ten times the concentration of hydrogen ions as a solution with a pH of 5.

Importance of pH

The pH of a solution is important in many areas of life, including chemistry, biology, and medicine. It can affect the rate of chemical reactions, the growth and survival of living organisms, and the effectiveness of medications.