Chapter 2: Acids, Bases and Salts
Taste and Indicators of Acids and Bases
Acids have a sour taste and turn blue litmus red, while bases taste bitter and turn red litmus blue. Indicators help us identify acidic or basic substances. These include natural indicators like turmeric and red cabbage, and synthetic ones like methyl orange and phenolphthalein. Some substances also act as olfactory indicators, changing their smell in acidic or basic environments.
Reactions with Metal Carbonates and Metal Hydrogencarbonates and Oxides
Acids react with metals to produce hydrogen gas and a salt. They also react with metal carbonates and bicarbonates, releasing carbon dioxide along with salt and water. When an acid and a base react, they undergo neutralization to form salt and water. Metallic oxides, which are basic, react with acids, while non-metallic oxides, which are acidic, react with bases.
Ionization, pH Scale, and Salts
In water, acids release hydrogen ions (H⁺) and bases release hydroxide ions (OH⁻), allowing the solution to conduct electricity. The strength of an acid or base is measured using the pH scale, where values below 7 indicate acidity, above 7 indicate basicity, and 7 is neutral. pH is important in many areas, such as digestion, agriculture, and environmental balance. Salts are formed through neutralization and can be acidic, basic, or neutral. Common salts like sodium chloride are used in daily life and serve as raw materials for other useful compounds like baking soda, washing soda, and plaster of Paris. Many salts also contain water of crystallization, which gives them their characteristic forms.