Acids, Bases and Salts | Class 10 Science Notes

2.2 What Do All Acids and All Bases Have in Common?

This section investigates the commonality among acids and bases, focusing on their ionic nature in aqueous solutions. It is observed that all acids produce hydrogen gas when reacting with metals, indicating the presence of hydrogen ions (H+). However, not all hydrogen-containing compounds are acidic; for example, glucose and alcohol do not show acidic behavior. Electrical conductivity experiments show that acids and bases conduct electricity in aqueous solutions due to the presence of ions, whereas solutions of glucose and alcohol do not conduct electricity. Acids produce H+ ions (or hydronium ions H3O+) in water, while bases produce hydroxide ions (OH-). The dissociation of acids and bases in water explains their characteristic properties and reactions. Dry hydrogen chloride gas does not show acidic behavior because H+ ions are produced only in the presence of water. The process of dissolving acids or bases in water is exothermic, releasing heat, which requires careful handling, especially for concentrated acids. Dilution reduces the concentration of H+ or OH- ions, decreasing the strength of the acid or base solution.

📊 Diagram: Figure 2.3 Acid solution in water conducts electricity; Figure 2.4 Preparation of HCl gas; Figure 2.5 Warning sign displayed on containers containing concentrated acids and bases.

🧪 Activity: Activity 2.8: Testing electrical conductivity of acids, bases, glucose, and alcohol; Activity 2.9: Preparation of HCl gas and testing its acidic nature; Activity 2.10: Mixing concentrated acid/base with water and observing temperature change.

🔗 Connection: Leads to understanding the pH scale and strength of acids and bases.