Question

In manufacture of glass _____ is the second largest constituent after silica.

• A. Cullet
• B. Soda
• C. Lime
• D. Magnesia

Hint:

Think of the common me "Soda-Lime-Silica glass".
The order of the components in the me reflects their relative abundance:
Silica is the highest ($>$70%), followed by Soda (~15%), and then Lime (~10%).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Glass is a widely used packaging material in the food industry due to its chemical inertness, impermeability, and ability to withstand thermal processing.
The most common type of glass used for commercial food containers is soda-lime-silica glass.

Step 2: Detailed Explation:
The raw materials used in glass manufacturing are:
1. Silica (Silicon Dioxide, \( \text{SiO}_2 \)): This is the primary structural network former, accounting for approximately 70% to 75% of the glass composition.
2. Soda (Sodium Oxide, \( \text{}_2\text{O} \)): Soda acts as a fluxing agent.
Because pure silica has an extremely high melting point (around \( 1700^\circ\text{C} \)), soda is added to lower the melting temperature to approximately \( 1000^\circ\text{C} \), making the manufacturing process more energy-efficient.
Soda is the second largest constituent, accounting for about 12% to 15% of the glass formulation.
3. Lime (Calcium Oxide, \( \text{CaO} \)): Lime acts as a stabilizer.
Without lime, soda-silica glass would dissolve in water.
Lime accounts for about 8% to 12% of the mixture.
Cullet is recycled crushed glass added to the raw batch to accelerate melting, but it is not classified as a primary chemical constituent.

Step 3: Fil Answer
The second largest chemical constituent in glass manufacturing after silica is Soda (Sodium Oxide).