Soda-lime glass is made by heating sand, sodium carbonate and limestone, while clay ceramics are fired in a furnace. Free notes and 15 questions answered.
Updated 19 Mar 2026 · Revise Right Team
Glass and Clay Ceramics is part of Using materials (chemistry only) in GCSE AQA Higher Chemistry.
4 min
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GCSE AQA Higher
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What this lesson covers
Soda-lime glass is made by heating sand, sodium carbonate and limestone, while clay ceramics are fired in a furnace. Free notes and 15 questions answered.
Describe the composition and properties of soda-lime glass and borosilicate glass
Explain how glass is manufactured from raw materials including sand, sodium carbonate and limestone
Compare the melting points and applications of different types of glass
Describe the process of making clay ceramics including pottery and bricks
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Use this lesson to stay inside Using materials (chemistry only) while connecting the detail back to the wider Topic 10: Using resources topic.
Topic 10: Using resources
Using materials (chemistry only)
GCSE AQA Higher Chemistry
Revision notes
Read the core explanations from Glass and Clay Ceramics before testing yourself from memory.
1. Glass and Clay Ceramics - Materials That Shape Our World
Look around you right now. The windows letting in light, the mug holding your tea, the bricks in the walls - they're all made from two of humanity's oldest materials: glass and ceramics. But here's what's fascinating: despite being used for thousands of years, the chemistry behind these materials is precisely controlled to give them exactly the properties we need.
Glass isn't just 'melted sand' - it's a carefully engineered mixture that determines whether your phone screen survives a drop or your oven door can handle 200°C. Clay ceramics aren't just 'baked mud' - the firing process creates entirely new chemical structures that make bricks strong enough to build skyscrapers.
2. The Two Types of Glass You Need to Know
Most of the glass we use every day is soda-lime glass. When you drink from a glass bottle or look through a window, you're using this material. The recipe is surprisingly simple: sand provides the main structure, sodium carbonate lowers the melting point (making it easier to work with), and limestone adds durability.
Borosilicate glass is the premium option. Made from sand and boron trioxide, it can handle much higher temperatures without cracking. This is why your Pyrex dishes can go from freezer to oven, and why chemistry labs use borosilicate beakers that won't shatter when heated.
3. How Glass is Made - From Sand to Window
Worked example: Manufacturing Soda-lime Glass
Describe the process of making soda-lime glass from raw materials
Mix sand (SiO₂), sodium carbonate (Na₂CO₃), and limestone (CaCO₃) — These three ingredients provide the basic structure and properties
Heat to approximately 1500°C in a furnace — High temperature melts the mixture and allows chemical reactions
Carbonates decompose: Na₂CO₃ → Na₂O + CO₂ and CaCO₃ → CaO + CO₂ — The oxides then combine with silica to form the glass structure
Pour molten glass into moulds or float on molten tin for flat sheets — Different shaping methods create different glass products
Controlled cooling prevents cracking and internal stress — This process is called annealing and is crucial for strong glass
Answer: Soda-lime glass is made by heating sand, sodium carbonate and limestone to 1500°C, allowing chemical reactions to form the glass structure, then shaping and cooling the product.
The key insight here is temperature control. Sodium carbonate acts as a flux - it lowers the melting point of pure sand from about 1700°C to 1500°C. Without it, glass-making would require much more energy and be far more difficult.
4. Clay Ceramics - From Mud to Building Materials
Clay ceramics follow a completely different process from glass. Instead of melting ingredients together, we start with clay - a naturally occurring material that becomes plastic when wet. The key scientific idea happens during firing, when heat transforms the clay's structure permanently.
Worked example: Making Clay Ceramics
Describe how pottery is made from clay
Mix clay with water to make it plastic and workable — Clay particles are flat and slide over each other when wet
Mould the wet clay into the desired shape (pot, brick, tile) — Clay can be shaped by hand, wheel, or pressing into moulds
Allow water to evaporate slowly to prevent cracking — Too-fast drying causes uneven shrinkage and cracks
Heat to 900-1200°C depending on the clay type — High temperature causes permanent chemical changes
Allow the ceramic to cool slowly in the furnace — Prevents thermal shock and cracking
Answer: Clay ceramics are made by shaping wet clay, drying it, then firing at high temperature in a furnace to create permanent chemical changes.
The firing process is where the real chemistry happens. Heat drives off remaining water and causes the clay particles to bond together permanently. This is why fired pottery can't be dissolved back into clay - the chemical structure has changed irreversibly.
5. Comparing Glass and Ceramics - Properties and Applications
Both glass and ceramics are incredibly useful, but they have different strengths. Understanding these differences explains why we use glass for windows but ceramics for building bricks, or why laboratory equipment might be glass but industrial furnace linings are ceramic.
Glass advantages: Transparent, can be recycled by remelting, smooth non-porous surface, can be shaped while molten. Glass disadvantages: Brittle, can shatter suddenly, limited heat resistance (except borosilicate).
Ceramic advantages: Very high heat resistance, excellent compressive strength, chemically inert, can be made porous or non-porous. Ceramic disadvantages: Opaque, brittle, difficult to recycle, limited shaping options after firing.
6. Exam Technique - Getting Full Marks on Glass and Ceramics
Exam questions on this topic often test your ability to link composition to properties, and properties to applications. The key is being specific about which type of glass or ceramic you're discussing, and explaining the chemistry behind the properties.
Common exam mistake: Students often confuse the compositions of soda-lime and borosilicate glass. Remember: soda-lime has three ingredients (sand, sodium carbonate, limestone), borosilicate has two (sand, boron trioxide). The 'soda' in soda-lime refers to sodium carbonate, not the drink!
Sources and content standards
Published by Revise Right. Use the official specification reference to check the requirements for your course. Content updated: 2026-03-19.
Soda-lime glass is made by heating a mixture of sand, sodium carbonate and limestone to approximately 1500°C in a furnace. The carbonates decompose and the oxides combine with silica to form the glass structure, which is then shaped in moulds or floated on molten tin and cooled slowly.
What is the difference between soda-lime and borosilicate glass?
Soda-lime glass is made from sand, sodium carbonate and limestone and is used for windows, bottles and everyday glassware. Borosilicate glass is made from sand and boron trioxide, melts at higher temperatures and resists cracking, so it is used for laboratory equipment and ovenware.
How are clay ceramics made?
Clay ceramics such as pottery, bricks and tiles are made by shaping wet clay, drying it slowly, then firing it in a furnace at 900-1200°C. The heat causes permanent chemical changes that bond the clay particles together, so fired pottery cannot be dissolved back into clay.
What is borosilicate glass made from?
Borosilicate glass is made from sand and boron trioxide. It melts at higher temperatures than soda-lime glass and can handle much higher temperatures without cracking, so it is used for laboratory equipment and ovenware.
What are the advantages and disadvantages of glass?
Glass is transparent, can be recycled by remelting, has a smooth non-porous surface and can be shaped while molten. Its disadvantages are that it is brittle, can shatter suddenly and has limited heat resistance, except for borosilicate glass.
What is soda-lime glass made from?
Soda-lime glass is made by heating a mixture of sand (silicon dioxide), sodium carbonate and limestone. It is the most common type of glass and is used for windows, bottles and everyday glassware.
What is annealing glass?
Annealing is the controlled, slow cooling of molten glass after it has been shaped. It prevents cracking and internal stress, and it is crucial for making strong glass.
What temperature are clay ceramics fired at?
Clay ceramics are fired in a furnace at 900-1200°C, depending on the clay type. The high temperature drives off remaining water and causes the clay particles to bond together permanently, which is why fired pottery cannot be dissolved back into clay.
What are the advantages and disadvantages of ceramics?
Ceramics have very high heat resistance, excellent compressive strength, are chemically inert and can be made porous or non-porous. Their disadvantages are that they are opaque, brittle, difficult to recycle and have limited shaping options after firing.
Why is sodium carbonate added to glass?
Sodium carbonate is added to glass because it acts as a flux, lowering the melting point of pure sand from about 1700°C to 1500°C. Without it, glass-making would require much more energy and be far more difficult.
What are ceramics in chemistry?
Clay ceramics are materials made by shaping wet clay and then heating it in a furnace, such as pottery, bricks and tiles. Firing causes permanent chemical changes, so ceramics have very high heat resistance, excellent compressive strength and are chemically inert, but they are opaque, brittle and difficult to recycle.
Why is borosilicate glass used in laboratories?
Borosilicate glass is used in laboratories because it is heat-resistant and melts at higher temperatures than soda-lime glass. Beakers made from it will not shatter when heated, and the same heat resistance lets ovenware go from freezer to oven.
What temperature is glass made at?
Soda-lime glass is made by heating sand, sodium carbonate and limestone to approximately 1500°C in a furnace. Sodium carbonate acts as a flux, lowering the melting point of pure sand from about 1700°C to 1500°C, so glass-making needs less energy.
Why does clay need to be dried slowly?
Clay is dried slowly so that water evaporates evenly and the shaped object does not crack. Drying too fast causes uneven shrinkage and cracks, and the fired ceramic is also cooled gradually in the furnace to prevent thermal shock.
What happens when clay is fired?
When clay is fired in a furnace, heat drives off the remaining water and causes the clay particles to bond together permanently. The chemical structure changes irreversibly, which is why fired pottery is strong and cannot be dissolved back into clay.