Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Limestone () is a naturally occurring mineral that undergoes calcination in a rotary kiln at to produce Quicklime ().
Quicklime () is an important industrial chemical used as a flux in metallurgy to remove acidic impurities like silica () and phosphorus pentoxide () by forming slag.
Slaked Lime () is produced by adding water to Quicklime, a process known as the 'slaking of lime', which is highly exothermic.
In the construction industry, lime is used in the manufacture of mortar (a mixture of , sand, and water) and as a key raw material for Portland cement.
Limestone is used in the manufacture of glass, specifically soda-lime glass, which consists of sodium and calcium silicates.
In the Solvay process for manufacturing , lime is used to recover ammonia () from ammonium chloride ().
Agricultural use: Lime is applied to soil to neutralize acidity and improve soil structure, providing essential ions for plant growth.
Sugar Industry: Milk of lime ( suspension) is used in the purification of sugar to precipitate impurities and neutralize organic acids.
📐Formulae
💡Examples
Problem 1:
Explain how Quicklime () acts as a flux in the extraction of Iron from its ore in a Blast Furnace.
Solution:
In the blast furnace, iron ore contains acidic impurities like silica (). Limestone () is added, which decomposes to . The then reacts with :
Explanation:
Quicklime () is a basic oxide. It reacts with the acidic impurity () to form Calcium Silicate (), which is a molten slag. This slag is lighter than molten iron and floats on top, allowing for easy removal.
Problem 2:
What happens when Carbon dioxide () is passed through lime water for a prolonged duration?
Solution:
Initially, lime water turns milky due to the formation of insoluble . On passing excess , the milkiness disappears due to the formation of soluble Calcium bicarbonate:
Explanation:
The primary reaction creates an insoluble white precipitate. The secondary reaction with excess converts the carbonate into a soluble hydrogen carbonate (), resulting in a clear solution.