Consider the following statements 1. Alkali is a base that dissolve in water. 2. Ca(OH), is not an example of Alkali. 3. Dissolution of a base in water is an exothermic process. How many of the statements given above are correct?

Alkalis

• Alkalis are water-soluble bases that produce hydroxide ions (OH⁻) when dissolved in water. They are a type of base that neutralizes acids to form water and a salt. Hence, Statement 1 is correct.

Common Alkalis

• Sodium Hydroxide (NaOH)
• Potassium Hydroxide (KOH)
• Calcium Hydroxide (Ca(OH)₂). Hence, Statement 2 is incorrect.
• Ammonium Hydroxide (NH₄OH)

Calcium Hydroxide

• Formula: Ca(OH)₂
• Common Name: Slaked lime or hydrated lime.
• Solubility: Slightly soluble in water, forming a basic solution known as limewater.
• pH: The aqueous solution of calcium hydroxide has a pH greater than 7, indicating its basic nature.
• Appearance: A white, odourless powder or a colourless solution.

Dissolution of Bases

• The dissolution of a base in water can be either exothermic or endothermic, depending on the specific base and the conditions of dissolution. Here’s a detailed explanation: Hence, Statement 3 is correct.

General Concept

• Exothermic Dissolution: An exothermic process releases heat when a substance dissolves in water. Examples of Bases:
• Sodium Hydroxide (NaOH): When sodium hydroxide dissolves in water, it releases heat, making the process exothermic.
• Calcium Oxide (CaO): When calcium oxide reacts with water to form calcium hydroxide, it also releases heat.
• Endothermic Dissolution: An endothermic process absorbs heat from its surroundings when a substance dissolves in water. Examples of Bases:
• Ammonium Hydroxide (NH₄OH): The dissolution of ammonia in water (forming ammonium hydroxide) absorbs heat, making the process endothermic.