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Questions on Expansion and Contraction

Q2.

(a) Name a type of glass that does allow boiling water to be safely poured into it - in fact that can be used on a flame to cook with!

Borosilicate glass - accept Pyrex

Borosilicate glass is a type of glass with silica and boron trioxide as the main glass-forming constituents. Borosilicate glasses are known for having very low coefficients of thermal expansion (~3 × 10−6 K−1 at 20 °C), making them resistant to thermal shock, more so than any other common glass. Borosilicate glass is sold under such trade names as Borcam, Borosil, DURAN, Suprax, Simax, BSA 60, BSC 51 (By NIPRO), Heatex, Endural, Schott, Refmex, Kimble, and some (but not all) items sold under the trade name Pyrex.

(b) How do you think this type of glass differs from ordinary glass to allow this?

It expands less when heated through a given temperature rise than ordinary glass. It has a lower co-efficient of expansion.

(c) How, in school science lessons, will you make use of this type of glassware?

In science we use beakers etc to heat water and flask to mix chemicals that undergo exothermic reactions - these are made of borosilicate glass.

(3 marks)