Page 12 - Curriculum Visions Dynamic Book

(Right) Thermometers are made of borosilicate glass so that expansion of the glass does not lead to inaccurate measurements of temperature.
(Left) Most laboratory glassware is made from borosilicate glass.
(Below) Borosilicate glass – often more commonly known by the trade name Pyrex®
– can be used for ovenware and even for glass saucepans (above right).
Making glass resist heat and cold
Glass behaves very differently than a metal. Most
glass cannot expand and contract safely with changing temperature in the way that a metal can. Soda lime glass, for example, has quite a high coefficient of thermal expansion, meaning that is shrinks markedly when cooled and swells when heated. At the same time, it does not conduct heat well, and it has a low fracture stress value (it breaks easily). As the temperature falls, stresses build up inside that can make it break. So, for example, if cold water is poured onto a sheet of hot soda glass, the glass will almost certainly shatter.
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