Question

Why an ordinary glass bottle cracks when boiling water is poured in it but a borosil bottle does not crack

Answer 1

A glass is made from liquid sand (silicon dioxide). Normal glass is an insulator i.e, it is a poor conductor of heat.

When a very hot liquid is poured into a glass tumbler, the surface of the glass which is in contact with the hot liquid heats up and expands as per its coefficient of thermal expansion. But the outer layer remains cold and does not expand since glass is a poor conductor and does not transfer the heat quickly. This causes the differential thermal expansion which eventually leads to cracking.

Borosilicate glass or Borosil glass is made up of boron trioxide and silicon dioxide. Borosilicate glasses are known for having very low coefficients of thermal expansion which makes them resistant to thermal shock, more than any other common glass. Borosil glass has a melting point of 820°C.

So, Borosil glass does not crack when hot liquid is poured in it, but normal glass cracks.

Answer 2

Answer:

Explanation:When a very hot liquid is poured into a glass tumbler, the surface of the glass which is in contact with the hot liquid heats up and expands as per its coefficient of thermal expansion. But the outer layer remains cold and does not expand since glass is a poor conductor and does not transfer the heat quickly. This causes the differential thermal expansion which eventually leads to cracking.