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Glass

8.2 Composition of Glass and Its Uses
CHEMISTRY • Form 4 • Chapter 8: Manufactured Substances in Industry

8.2Composition of Glass and Its Uses

Glass is a versatile manufactured substance widely used in architectural structures, laboratory equipment, optical instruments, and everyday household items. When silica is heated together with other chemicals, various types of glass with distinct characteristics are formed.

Learning Objectives

  • Describe briefly with examples the type of glass, their composition, properties and uses.

Mind Map of the 4 Main Types of Glass

A clear comparison of compositions, unique properties, and specific applications for each type of glass.

Type of Glass Composition Key Properties Uses
Fused Silica Glass Silica only, \(\text{SiO}_2\) High melting point, around \(1800\ ^\circ\text{C}\); minimal expansion or contraction Telescope lenses
Soda-lime Glass \(\text{SiO}_2\), \(\text{Na}_2\text{CO}_3\), \(\text{CaCO}_3\) Melts around \(1000\ ^\circ\text{C}\); easily moulded; cracks under sudden temperature change Bottles and jugs
Borosilicate Glass \(\text{SiO}_2\), \(\text{Na}_2\text{CO}_3\), \(\text{CaCO}_3\), \(\text{B}_2\text{O}_3\), \(\text{Al}_2\text{O}_3\) High heat resistance; low expansion coefficient; resists thermal stress Laboratory beakers and flasks
Lead Crystal Glass \(\text{SiO}_2\), \(\text{Na}_2\text{CO}_3\), \(\text{PbO}\) Soft, dense, heavy; high refractive index Prisms

Brief Explanation

Understand how different glass compositions create different properties.

Silica is the main component present in all types of glass. When silica is heated either alone or combined with other chemical compounds, different types of glass are formed.

1. Fused Silica Glass

Made from pure \(\text{SiO}_2\) without adding any other chemical. It requires a very high melting temperature of around \(1800\ ^\circ\text{C}\) and has minimal thermal expansion, making it ideal for precision lenses such as those in telescopes.

2. Soda-lime Glass

Made from \(\text{SiO}_2\), soda \(\text{Na}_2\text{CO}_3\), and limestone \(\text{CaCO}_3\). Soda lowers the melting point of silica to around \(1000\ ^\circ\text{C}\), making it easily moulded into bottles and jugs, but it cracks easily under sudden temperature changes.

3. Borosilicate Glass

Made from \(\text{SiO}_2\), \(\text{Na}_2\text{CO}_3\), \(\text{CaCO}_3\), boron oxide \(\text{B}_2\text{O}_3\), and aluminium oxide \(\text{Al}_2\text{O}_3\). Its low expansion coefficient prevents thermal shock cracking, making it suitable for laboratory beakers and flasks.

4. Lead Crystal Glass

Made from \(\text{SiO}_2\), \(\text{Na}_2\text{CO}_3\), and lead(II) oxide \(\text{PbO}\). Lead replaces calcium to produce glass that is softer, denser, heavier, and has a high refractive index, making it suitable for prisms.

Basic Property of Glass Description
Hard but brittleGlass is hard, yet it can break or shatter easily when struck.
Chemically inertGlass does not react easily with most chemicals.
TransparentLight can pass through glass, making it useful for windows and lenses.
WaterproofGlass does not allow water to pass through it.
Heat insulatorGlass is a poor conductor of heat.
Electrical insulatorGlass does not conduct electricity.

Try to Answer First

Answer mentally, then check the explanation.

1

What is the main component present in all types of glass?

Answer: Silica (silicon dioxide, \(\text{SiO}_2\)).
2

Why can borosilicate glass be taken out from a refrigerator and heated directly without cracking?

Answer: It has a low expansion coefficient and high resistance to thermal stress.
3

What is the function of soda (\(\text{Na}_2\text{CO}_3\)) in the production of soda-lime glass?

Answer: It lowers the melting point of silica (\(\text{SiO}_2\)) from around \(1800\ ^\circ\text{C}\) to around \(1000\ ^\circ\text{C}\).

Common Mistakes

Avoid these errors when comparing the types of glass.

!
Confusing the composition of soda-lime glass with borosilicate glass by forgetting that borosilicate glass contains \(\text{B}_2\text{O}_3\) and \(\text{Al}_2\text{O}_3\).
!
Assuming soda-lime glass can withstand sudden extreme temperature changes like laboratory glassware.
!
Thinking lead crystal glass is harder than normal glass, whereas the addition of lead actually makes it softer and denser.

Concept Misunderstandings

Compare each misconception with the correct fact.

Misconception

All types of glass expand and contract significantly when heated.

Correct Fact

Fused silica glass and borosilicate glass have very low coefficients of thermal expansion, meaning they barely expand or contract upon heating, preventing thermal cracking.

Misconception

Soda-lime glass and fused silica glass have the same melting point.

Correct Fact

Fused silica glass has a very high melting point of around \(1800\ ^\circ\text{C}\), while the addition of soda (\(\text{Na}_2\text{CO}_3\)) lowers the melting point of soda-lime glass to around \(1000\ ^\circ\text{C}\).

Summary

Key facts to remember.

  • All glass types share basic properties: transparent, waterproof, hard but brittle, chemically inert, heat insulators, and electrical insulators.
  • Fused silica glass: Pure \(\text{SiO}_2\), high melting point (\(1800\ ^\circ\text{C}\)), minimal expansion/contraction, used for telescope lenses.
  • Soda-lime glass: \(\text{SiO}_2\), \(\text{Na}_2\text{CO}_3\), \(\text{CaCO}_3\), low melting point (\(1000\ ^\circ\text{C}\)), easily moulded, prone to thermal cracking, used for bottles and jugs.
  • Borosilicate glass: \(\text{SiO}_2\), \(\text{Na}_2\text{CO}_3\), \(\text{CaCO}_3\), \(\text{B}_2\text{O}_3\), \(\text{Al}_2\text{O}_3\), heat-resistant with low expansion coefficient, used for laboratory glassware.
  • Lead crystal glass: \(\text{SiO}_2\), \(\text{Na}_2\text{CO}_3\), \(\text{PbO}\), soft, dense, heavy with a high refractive index, used for prisms.

Short Activity

Complete all parts before checking your score.

A. Objective Quiz

1

Which of the following substances replaces calcium in glass to give it a higher density and a high refractive index suitable for prisms?

2

Why is borosilicate glass commonly used to manufacture laboratory beakers and flasks?

B. Fill in the Blanks

3

In the manufacturing of soda-lime glass, adding soda (\(\text{Na}_2\text{CO}_3\)) lowers the melting point of silica to around ______ °C.

4

Fused silica glass is made from silicon dioxide without adding any other chemical and is suitable to be used in making ______ lens.

C. Match the Type of Glass with Its Characteristic

Drag each glass type on desktop. On mobile, tap a glass type and then tap the matching box.

Type of Glass

Fused silica glass Soda-lime glass Borosilicate glass Lead crystal glass

Characteristic / Composition

1Made purely of \(\text{SiO}_2\) and has a melting point around \(1800\ ^\circ\text{C}\)
2Easily moulded into bottles and jugs but cracks easily under sudden temperature changes
3Contains \(\text{B}_2\text{O}_3\) and \(\text{Al}_2\text{O}_3\), possessing a low expansion coefficient
4Soft, heavy glass with a high refractive index used to make prisms
Complete every answer before checking.
 

Keywords

Tap or hover over a term to read its meaning.

Silica (\(\text{SiO}_2\)) Fused silica glass Soda-lime glass Borosilicate glass Lead crystal glass Thermal stress Expansion coefficient Refractive index
The views expressed in the notes here are those of the contributor and don’t necessarily represent the views of Pandai.

Glass

8.2 Composition of Glass and Its Uses
CHEMISTRY • Form 4 • Chapter 8: Manufactured Substances in Industry

8.2Composition of Glass and Its Uses

Glass is a versatile manufactured substance widely used in architectural structures, laboratory equipment, optical instruments, and everyday household items. When silica is heated together with other chemicals, various types of glass with distinct characteristics are formed.

Learning Objectives

  • Describe briefly with examples the type of glass, their composition, properties and uses.

Mind Map of the 4 Main Types of Glass

A clear comparison of compositions, unique properties, and specific applications for each type of glass.

Type of Glass Composition Key Properties Uses
Fused Silica Glass Silica only, \(\text{SiO}_2\) High melting point, around \(1800\ ^\circ\text{C}\); minimal expansion or contraction Telescope lenses
Soda-lime Glass \(\text{SiO}_2\), \(\text{Na}_2\text{CO}_3\), \(\text{CaCO}_3\) Melts around \(1000\ ^\circ\text{C}\); easily moulded; cracks under sudden temperature change Bottles and jugs
Borosilicate Glass \(\text{SiO}_2\), \(\text{Na}_2\text{CO}_3\), \(\text{CaCO}_3\), \(\text{B}_2\text{O}_3\), \(\text{Al}_2\text{O}_3\) High heat resistance; low expansion coefficient; resists thermal stress Laboratory beakers and flasks
Lead Crystal Glass \(\text{SiO}_2\), \(\text{Na}_2\text{CO}_3\), \(\text{PbO}\) Soft, dense, heavy; high refractive index Prisms

Brief Explanation

Understand how different glass compositions create different properties.

Silica is the main component present in all types of glass. When silica is heated either alone or combined with other chemical compounds, different types of glass are formed.

1. Fused Silica Glass

Made from pure \(\text{SiO}_2\) without adding any other chemical. It requires a very high melting temperature of around \(1800\ ^\circ\text{C}\) and has minimal thermal expansion, making it ideal for precision lenses such as those in telescopes.

2. Soda-lime Glass

Made from \(\text{SiO}_2\), soda \(\text{Na}_2\text{CO}_3\), and limestone \(\text{CaCO}_3\). Soda lowers the melting point of silica to around \(1000\ ^\circ\text{C}\), making it easily moulded into bottles and jugs, but it cracks easily under sudden temperature changes.

3. Borosilicate Glass

Made from \(\text{SiO}_2\), \(\text{Na}_2\text{CO}_3\), \(\text{CaCO}_3\), boron oxide \(\text{B}_2\text{O}_3\), and aluminium oxide \(\text{Al}_2\text{O}_3\). Its low expansion coefficient prevents thermal shock cracking, making it suitable for laboratory beakers and flasks.

4. Lead Crystal Glass

Made from \(\text{SiO}_2\), \(\text{Na}_2\text{CO}_3\), and lead(II) oxide \(\text{PbO}\). Lead replaces calcium to produce glass that is softer, denser, heavier, and has a high refractive index, making it suitable for prisms.

Basic Property of Glass Description
Hard but brittleGlass is hard, yet it can break or shatter easily when struck.
Chemically inertGlass does not react easily with most chemicals.
TransparentLight can pass through glass, making it useful for windows and lenses.
WaterproofGlass does not allow water to pass through it.
Heat insulatorGlass is a poor conductor of heat.
Electrical insulatorGlass does not conduct electricity.

Try to Answer First

Answer mentally, then check the explanation.

1

What is the main component present in all types of glass?

Answer: Silica (silicon dioxide, \(\text{SiO}_2\)).
2

Why can borosilicate glass be taken out from a refrigerator and heated directly without cracking?

Answer: It has a low expansion coefficient and high resistance to thermal stress.
3

What is the function of soda (\(\text{Na}_2\text{CO}_3\)) in the production of soda-lime glass?

Answer: It lowers the melting point of silica (\(\text{SiO}_2\)) from around \(1800\ ^\circ\text{C}\) to around \(1000\ ^\circ\text{C}\).

Common Mistakes

Avoid these errors when comparing the types of glass.

!
Confusing the composition of soda-lime glass with borosilicate glass by forgetting that borosilicate glass contains \(\text{B}_2\text{O}_3\) and \(\text{Al}_2\text{O}_3\).
!
Assuming soda-lime glass can withstand sudden extreme temperature changes like laboratory glassware.
!
Thinking lead crystal glass is harder than normal glass, whereas the addition of lead actually makes it softer and denser.

Concept Misunderstandings

Compare each misconception with the correct fact.

Misconception

All types of glass expand and contract significantly when heated.

Correct Fact

Fused silica glass and borosilicate glass have very low coefficients of thermal expansion, meaning they barely expand or contract upon heating, preventing thermal cracking.

Misconception

Soda-lime glass and fused silica glass have the same melting point.

Correct Fact

Fused silica glass has a very high melting point of around \(1800\ ^\circ\text{C}\), while the addition of soda (\(\text{Na}_2\text{CO}_3\)) lowers the melting point of soda-lime glass to around \(1000\ ^\circ\text{C}\).

Summary

Key facts to remember.

  • All glass types share basic properties: transparent, waterproof, hard but brittle, chemically inert, heat insulators, and electrical insulators.
  • Fused silica glass: Pure \(\text{SiO}_2\), high melting point (\(1800\ ^\circ\text{C}\)), minimal expansion/contraction, used for telescope lenses.
  • Soda-lime glass: \(\text{SiO}_2\), \(\text{Na}_2\text{CO}_3\), \(\text{CaCO}_3\), low melting point (\(1000\ ^\circ\text{C}\)), easily moulded, prone to thermal cracking, used for bottles and jugs.
  • Borosilicate glass: \(\text{SiO}_2\), \(\text{Na}_2\text{CO}_3\), \(\text{CaCO}_3\), \(\text{B}_2\text{O}_3\), \(\text{Al}_2\text{O}_3\), heat-resistant with low expansion coefficient, used for laboratory glassware.
  • Lead crystal glass: \(\text{SiO}_2\), \(\text{Na}_2\text{CO}_3\), \(\text{PbO}\), soft, dense, heavy with a high refractive index, used for prisms.

Short Activity

Complete all parts before checking your score.

A. Objective Quiz

1

Which of the following substances replaces calcium in glass to give it a higher density and a high refractive index suitable for prisms?

2

Why is borosilicate glass commonly used to manufacture laboratory beakers and flasks?

B. Fill in the Blanks

3

In the manufacturing of soda-lime glass, adding soda (\(\text{Na}_2\text{CO}_3\)) lowers the melting point of silica to around ______ °C.

4

Fused silica glass is made from silicon dioxide without adding any other chemical and is suitable to be used in making ______ lens.

C. Match the Type of Glass with Its Characteristic

Drag each glass type on desktop. On mobile, tap a glass type and then tap the matching box.

Type of Glass

Fused silica glass Soda-lime glass Borosilicate glass Lead crystal glass

Characteristic / Composition

1Made purely of \(\text{SiO}_2\) and has a melting point around \(1800\ ^\circ\text{C}\)
2Easily moulded into bottles and jugs but cracks easily under sudden temperature changes
3Contains \(\text{B}_2\text{O}_3\) and \(\text{Al}_2\text{O}_3\), possessing a low expansion coefficient
4Soft, heavy glass with a high refractive index used to make prisms
Complete every answer before checking.
 

Keywords

Tap or hover over a term to read its meaning.

Silica (\(\text{SiO}_2\)) Fused silica glass Soda-lime glass Borosilicate glass Lead crystal glass Thermal stress Expansion coefficient Refractive index
The views expressed in the notes here are those of the contributor and don’t necessarily represent the views of Pandai.
Chapter : Manufactured Substances in Industry
Topic : Describe with examples the type of glass, their composition, properties and uses
Form 4 Chemistry
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