Chapter 10, Problem 1CQ

(a) Why does an ordinary glass dish usually break when placed on a hot stove? (b) Dishes made of Pyrex glass don’t break as easily. What characteristic of Pyrex prevents breakage?

To determine

Why an ordinary glass breaks when placed on a hot stove.

Explanation of Solution

Any material upon heating will expand. The expansion depends on the temperature and the co-efficient of expansion ( $\alpha$).

The co-efficient of expansion refers to the change in length per degree rise in temperature. Glass has a relatively higher co-efficient of linear expansion.

Conclusion: As the temperature of the glass increases upon heating, there is a stress that eventually builds up. This causes the glass to expand first. Further heating causes the glass to break.

To determine

The characteristic of Pyrex that prevents breakage.

Explanation of Solution

Any material upon heating will expand. The expansion depends on the temperature and the co-efficient of expansion ( $\alpha$).

The co-efficient of expansion refers to the change in length per degree rise in temperature. Pyrex has a relatively lesser co-efficient of linear expansion than Glass.

Conclusion: As the temperature of the pyrex increases, there is not much stress that is present when compared to glass. This is due to the lower value of $\alpha$.