Question - What is a base? Explain its properties and uses.

🧴Definition of Alkali🧴 

An alkali is a chemical substance. It turns red litmus paper blue and has a bitter taste.

⚗️ Reaction with Acids ⚗️ 

Acids and alkalis are opposites. When they react with each other, they neutralize each other's effects. The acid cancels the effect of the alkali, and the alkali cancels the effect of the acid. As a result of this reaction, salt and water are formed. This reaction between acid and alkali is called a neutralization reaction.

💧Reaction with Water💧

Alkalis produce hydroxide ions (OH⁻) in water. Alkalis that dissolve in water are called bases. All acids produce H⁺(aq) ions and all alkalis produce OH⁻(aq) ions in water.

🧪 Indicators 🧪 

When soap with alkaline properties is applied to a vegetable stain on clothes, the stain turns reddish-brown.

👃 Olfactory Indicators 👃 

Some substances change their smell slightly in acidic or alkaline mediums. These are called olfactory indicators.

🔩 Reaction with Metallic Oxides (Alkalis) 🔩

 Calcium hydroxide, an alkali, reacts with carbon dioxide to form salt and water. Thus, we conclude that non-metallic oxides are acidic in nature, while metallic oxides are alkaline.

📏 pH Scale 📏

pH is an indicator derived from the German word "potenz," meaning "power." A scale has been developed to measure the concentration of hydrogen ions in a solution, called the pH scale.

The pH scale ranges from 0 (high acidity) to 14 (high alkalinity). In simple terms, pH is a number that indicates whether a solution is acidic or alkaline. 

If the pH value is less than 7, the solution is acidic. If the pH value is more than 7, the solution is alkaline.