Factors of a test tube being cracked.

2008-09-02 3:46 am

What will make an experimenting test tube to crack? A test tube that is being heated and the water in it boils. The water then condenses on the upepr part of that test tube and flows back to the hot part of the test tube. Then, according to my book, it cracks. Why????

回答 (1)

Uncle Michael

2008-09-02 7:43 am

✔ 最佳答案

When the test tube is heated, the temperature of the glass of the test tube is high.

When the heated test tube is put into water, the temperature of outer wall of the test tube drops suddenly. The outer wall of the test tube thus sharply contracts due to the sharp decrease in temperature. However, the inner wall of test tube remains at high temperature and its contraction is insignificant. The great difference in contraction between the inner wall and outer wall of the test tube exerts a force on the glass and consequently cracks the test tube.
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