Properties of Acids and Bases
Acids are sour to taste, turn blue litmus paper red, and release hydrogen ions (H⁺) when dissolved in water. Strong acids, like Hydrochloric Acid (HCl), completely dissociate in water, while weak acids, like Acetic Acid (CH₃COOH), only partially dissociate. Bases are bitter to taste, feel soapy, turn red litmus blue, and release hydroxide ions (OH⁻) in water. Bases that dissolve in water are called alkalis (e.g., Sodium Hydroxide, NaOH).
Chemical Reactions
When an acid reacts with a metal, it produces a salt and hydrogen gas (Acid + Metal → Salt + H₂). When acids and bases react with each other, they neutralize each other's effects to form a salt and water (Acid + Base → Salt + Water). This is known as a Neutralization Reaction.
The pH Scale
The pH scale measures the hydrogen ion concentration in a solution, ranging from 0 to 14. A pH of 7 is completely neutral (pure water). A pH less than 7 indicates an acidic solution, while a pH greater than 7 indicates a basic (alkaline) solution. The lower the pH, the stronger the acid; the higher the pH, the stronger the base. Our bodies function optimally within a narrow pH range of 7.0 to 7.8.
Important Salts in Daily Life
Salts are ionic compounds formed by the neutralization of acids and bases. Several important salts are derived from common salt (Sodium Chloride, NaCl):
- Sodium Hydroxide (NaOH): Produced via the chlor-alkali process, used in making soaps and detergents.
- Bleaching Powder (CaOCl₂): Used for disinfecting drinking water and bleaching cotton.
- Baking Soda (NaHCO₃): A mild non-corrosive basic salt used in cooking to make cakes spongy, and as an antacid.
- Washing Soda (Na₂CO₃·10H₂O): Used in the glass, soap, and paper industries, and for removing permanent hardness of water.