eli5: Why is it that glass shatters when it goes from extremely hot to extremely cold temperatures and vice versa? Moreover, what does that say about the glass manufacturing process if anything? Thank you!

Question

I just saw a video of people shattering Pyrex glass by pouring ice cold water within the measuring cup after heating it with a blowtorch, and I am curious as to what causes the shattering!

Here’s a link to the video if anyone is interested:

Thanks in advance to anyone responding!

In: Chemistry

Answer 1

So heating things cause then to expand and cooling them makes them shrink. Using a blowtorch is applying a lot of heat to a small area very fast. This causes the hot area to expand but the cold area doesn’t so the glass has no where to go and shatters. As long as the glass is heated evenly it won’t shatter so you can use a glass dish in the oven but not on a stove top.