Soda-lime glass

Soda-lime glass is the cheap, everyday glass made from silica, sodium carbonate and limestone. It is by far the most widely produced type of glass. Malay: kaca soda-kapur · Chinese: 钠钙玻璃.

The three raw materials each play a part. Silica, which is silicon dioxide, SiO₂, is the main glass-former; sodium carbonate, the soda, lowers the melting temperature so the mixture is easier and cheaper to melt; and limestone, which is calcium carbonate, makes the glass more durable and less soluble. Once cooled, soda-lime glass is transparent, hard and easy to shape while hot, which is why it suits mass-produced items. Its main limitation is that it expands quite a lot when heated, so it can crack if it is heated or cooled suddenly.

Example. Soda-lime glass is used for drink bottles and jars, window panes and light bulbs, all of which are made in huge numbers and do not need to survive rapid temperature change. Its low cost is the reason it is chosen for these everyday products.

Confusion to avoid. Do not confuse soda-lime glass with borosilicate glass. Soda-lime glass is cheap but cracks under sudden temperature change, while borosilicate glass contains boron oxide and withstands sudden heating and cooling, which is why laboratory glassware is borosilicate rather than soda-lime.

A common exam pairing asks you to give one use of soda-lime glass and explain why it is suitable, then contrast it with a use that would need borosilicate glass instead. Being ready with a bottle or a window pane for the first, and heat-resistant laboratory glassware for the second, keeps that answer both quick and accurate under time pressure.

Knowing the raw materials of soda-lime glass and contrasting it with borosilicate glass is a common short-answer pairing in SPM Chemistry.