Why does a glass tumbler break when boiling water directly poured into it?

Answer 1

When heat is applied to something, it tends to expand. When you pour hot water into something made out of glass, only the inside dilates, and the outside doesn't, since its temperature is cooler. If the insides enlarges but the outside doesn't, it cracks. For this reason thick glass is more likely to crack, and thinner glass is less likely.

Also, the bottom of the glass could expand, while the top doesn't (if the hot water goes straight to the bottom). In any case, the temperature is higher in one part of the glass and lower in another, so one part expands and another stays the same size.

Answer 2

When hot liquid is poured into a thick glass tumbler, it cracks because the glass is a poor conductor of heat. When hot liquid is poured into the tumbler, the inner surface of the tumbler becomes hot, while the outer surface remains at room temperature. Therefore, the inner surface of the tumbler expands, while the outer surface does not expand. This unequal expansion cracks the tumbler.

Answer 3

Because when the glass on the inside and at the bottom of the tumbler are quickly heated by the water, they expand faster than the adjacent areas of the tumbler and the areas must separate. If the tumbler is heated more slowly before pouring hot water into it, it will not crack.

Answer 4

The hot water causes the parts of the glass it comes into contact with to expand. This causes stress between the cold and hot area and if this stress is high enough the fabric of the glass shatters.

If glass is to be used to contain hot liquids it should be gradually warmed to the temperature of that liquid so that the stress does not occur.

Answer 5

Matter expands when it is heated. When you pour boiling water into a glass the bottom becomes heated and expands while the rest of the glass is at a different temperature. As the bottom of the glass expands it literally expands and causes stress in the glass that is eventually enough to fracture the bond between the glass molecules, causing a crack. If you heat the glass more evenly it will expand evenly, preventing that stress from happening. Slow and even temperature changes will prevent the breaking.

Answer 6

The boiling water will cause the inner surface of the glass to rapidly expand, while the outer surface would be much slower to expand. It is this inconsistency of expansion that causes stress in the wall of the thick tumbler. Modern glass recipes are less likely to be stressed enough to shatter. Thin tumblers will have both inner and outer surfaces expanding at almost the same time, so are unlikely to shatter.

Answer 7

It is due to uneven thermal expansion. When hot water is poured into the tumbler, the inside surface heats up. As it does so, it wants to expand. But the thickness of the tumbler means that the outer parts have not yet got hot enough to expand. There is, therefore a tension between the inner layers of glass wanting to expand outwards and the outer layer wanting to stay put. It is this tension which eventually causes cracking.

Answer 8

The inside of the tumbler is hot and the outside is cool due to the poor thermal conductivity of the glass; this temperature gradient causes a tensile stress on the outside surface where small surface defects exist, which will crack the tumbler.

Answer 9

The inner glass layer expands when hot water is poured into it while the outer layer is still cool, hence the glass cracks

Answer 10

When materials are heated they expand, when the expansion is too quick in some materials such as amorphous silica (glass) the structure breaks.