Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Neutralisation is a chemical reaction where an acid and a base react with each other to form salt and water, with the evolution of heat. The general equation is: .
Indigestion: Our stomach contains Hydrochloric acid () to help digest food. Too much acid causes indigestion. To relieve it, we take an antacid such as 'Milk of Magnesia', which contains Magnesium hydroxide (), a base that neutralises the excess acid.
Ant Sting: The sting of an ant contains Formic acid (). The effect of the acid can be neutralised by rubbing moist baking soda (Sodium hydrogen carbonate, ) or calamine solution, which contains Zinc carbonate ().
Soil Treatment: Plants do not grow well if the soil is too acidic or too basic. Acidic soil is treated with bases like Quicklime (Calcium oxide, ) or Slaked lime (Calcium hydroxide, ). If the soil is basic, organic matter (compost) is added as it releases acids to neutralise the soil.
Factory Waste: The wastes of many factories contain acids. If allowed to flow into water bodies, these acids will kill fish and other organisms. Therefore, factory wastes are neutralised by adding basic substances before disposal.
📐Formulae
💡Examples
Problem 1:
A person suffering from acidity is advised to take an antacid tablet. Explain the chemical process occurring in the stomach using the example of Magnesium hydroxide ().
Solution:
Explanation:
The stomach contains excess Hydrochloric acid (), which causes pain. The antacid contains Magnesium hydroxide, which is a base. It reacts with the acid to form Magnesium chloride (a salt) and water, thereby neutralising the acidity.
Problem 2:
Why is calamine solution applied on the skin when an ant bites?
Solution:
The Formic acid () from the sting is neutralised by Zinc carbonate () present in the calamine.
Explanation:
Ant stings inject acidic liquid into the skin. Calamine solution is basic in nature. When applied, it undergoes a neutralisation reaction with the formic acid, providing relief from the irritation.