Among the following glassess, which type is used for making superior type laboratory apparatus?

Options:

• Pyrex glass
• Hard glass
• Soda lime glass
• Flint glass

Answer: Pyrex glass

Pyrex glass:

It is interesting to note the properties & composition of pyrex glass. The most important property of pyrex glass is that it has low coefficient of expansion. Do you know anything about the composition of pyrex glass. The composition of pyrex glass includes

• Silica 80%
• Al₂O₃ 3%
• B₂O₃ 12%
• CaO 0.5%

Hard glass:

Hard glass is also known as potash glass. Remember that hard glass has a higher melting point. Also note that if we use K₂CO₃ instead of Na₂CO₃ in the manufacturing process the product obtained is known as hard glass.

Flint glass:

Flint glass is used in making prisms because of its high refractive index.