# Expansion & contraction due to temperature **URL:** \ **Category:** Factual Questions\ **Created:** [December 23, 2000, 3:39am UTC](https://boards.straightdope.com/t/expansion-contraction-due-to-temperature/46959 "2000-12-23T03:39:16Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![FEotU](https://avatars.discourse-cdn.com/v4/letter/f/b9bd4f/32.png) [@FEotU](https://boards.straightdope.com/u/FEotU)\ **Post date:** [December 23, 2000, 3:39am UTC](https://boards.straightdope.com/t/expansion-contraction-due-to-temperature/46959/1 "2000-12-23T03:39:16Z")
This may be a dumb question (probably I skipped the Chem. class that explained this), but since heat causes things to expand, and cold causes them to contract, why does water expand when you freeze it? ---
**Author:** ![andyman](https://avatars.discourse-cdn.com/v4/letter/a/8491ac/32.png) [@andyman](https://boards.straightdope.com/u/andyman)\ **Post date:** [December 23, 2000, 3:54am UTC](https://boards.straightdope.com/t/expansion-contraction-due-to-temperature/46959/2 "2000-12-23T03:54:25Z")
As explained to me by my 3.8 average physics major sister: When water freezes is forms a “lattice” or crystaline structure. This forms spaces between the molecules and expands the volume. It is one of the few substances that takes up more volume as a solid. 🙂 ---
**Author:** ![peace](https://avatars.discourse-cdn.com/v4/letter/p/c68b51/32.png) [@peace](https://boards.straightdope.com/u/peace)\ **Post date:** [December 23, 2000, 3:57am UTC](https://boards.straightdope.com/t/expansion-contraction-due-to-temperature/46959/3 "2000-12-23T03:57:24Z")
## Is it my foggy memory or is it true: cast iron is another rare substance that takes less volume when liquid? Peace ---
**Author:** ![Ringo](https://avatars.discourse-cdn.com/v4/letter/r/779978/32.png) [@Ringo](https://boards.straightdope.com/u/Ringo)\ **Post date:** [December 23, 2000, 4:06am UTC](https://boards.straightdope.com/t/expansion-contraction-due-to-temperature/46959/4 "2000-12-23T04:06:56Z")
Previous threads addressing the subject: [expanding freezing water](http://boards.straightdope.com/sdmb/showthread.php?threadid=39895) [ice rises](http://boards.straightdope.com/sdmb/showthread.php?threadid=28870) [Growing Ice](http://boards.straightdope.com/sdmb/showthread.php?threadid=7645) [Expanding Icecubes](http://boards.straightdope.com/sdmb/showthread.php?threadid=6045) I’m not readily recalling a liquid form of cast iron. Perhaps you meant molten iron? ---
**Author:** ![peace](https://avatars.discourse-cdn.com/v4/letter/p/c68b51/32.png) [@peace](https://boards.straightdope.com/u/peace)\ **Post date:** [December 23, 2000, 4:38am UTC](https://boards.straightdope.com/t/expansion-contraction-due-to-temperature/46959/5 "2000-12-23T04:38:24Z")
## Beatle, I mean that cast iron, like ice, takes more volume when it is solid, compared with its liquid form, whatever you call it. If this is clear , do you know the answer? Peace ---
**Author:** ![Ringo](https://avatars.discourse-cdn.com/v4/letter/r/779978/32.png) [@Ringo](https://boards.straightdope.com/u/Ringo)\ **Post date:** [December 23, 2000, 4:54am UTC](https://boards.straightdope.com/t/expansion-contraction-due-to-temperature/46959/6 "2000-12-23T04:54:31Z")
[Cast Iron liquid and solid density](http://homepage.ntlworld.com/oxfordtours/workitoutnet/castaid/spruecalculator/decinote.htm) includes this line: > [@](#): > > assumes liquid dens. =0.9xsolid dens. which I read as saying the liquid form is _less_ dense than the solid, which would make it like everything else except water/ice. That page is a bit obtuse. You through me with your mention of liquid cast iron because, if it’s liquid, i.e., molten, it’s not cast, yet. ---
**Author:** ![peace](https://avatars.discourse-cdn.com/v4/letter/p/c68b51/32.png) [@peace](https://boards.straightdope.com/u/peace)\ **Post date:** [December 23, 2000, 5:15am UTC](https://boards.straightdope.com/t/expansion-contraction-due-to-temperature/46959/7 "2000-12-23T05:15:41Z")
## Beatle, sorry for the confusion. As I said, my memory is rusty (no pun intended), but somehow I remembered it specifically about cast iron. Probably, I should’ve said “iron”. From that page, it looks like any iron is less dense liquid than solid, which will cause solid iron sink. Is this the case? Peace ---
**Author:** ![Una\_Persson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/una_persson/32/346_2.png) [@Una\_Persson](https://boards.straightdope.com/u/Una_Persson)\ **Post date:** [December 23, 2000, 3:40pm UTC](https://boards.straightdope.com/t/expansion-contraction-due-to-temperature/46959/8 "2000-12-23T15:40:18Z")
> [@](#): > > ## \*Originally posted by peace \* \*\*From that page, it looks like any iron is less dense liquid than solid, which will cause solid iron sink. Is this the case? > > Peace \*\* Barring surface tension effects and/or presence of a slag coating, the solid should sink if it is denser.