# How fast does dry ice melt?

**URL:** <https://boards.straightdope.com/t/how-fast-does-dry-ice-melt/73981>\
**Category:** Factual Questions\
**Created:** [July 27, 2001, 4:47pm UTC](https://boards.straightdope.com/t/how-fast-does-dry-ice-melt/73981 "2001-07-27T16:47:56Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![McMurphy](https://avatars.discourse-cdn.com/v4/letter/m/e19adc/32.png) [@McMurphy](https://boards.straightdope.com/u/McMurphy)\
**Post date:** [July 27, 2001, 4:47pm UTC](https://boards.straightdope.com/t/how-fast-does-dry-ice-melt/73981/1 "2001-07-27T16:47:56Z")

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If I had a 10lb solid block of dry ice stored in deep freeze and I took it out and placed it in a room at normal room temperature, how long would it take to melt?

Also, is it possible to freeze things _inside_ a block of dry ice as it is with normal ice (think David Blaine & his iceman trick)?

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**Author:** ![Fish42](https://avatars.discourse-cdn.com/v4/letter/f/4da419/32.png) [@Fish42](https://boards.straightdope.com/u/Fish42)\
**Post date:** [July 27, 2001, 4:56pm UTC](https://boards.straightdope.com/t/how-fast-does-dry-ice-melt/73981/2 "2001-07-27T16:56:39Z")

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I’ll admit this is nitpicking, but…

At room temperature & atmospheric pressure, dry ice doesn’t melt; it sublimates (changes from solid directly to a gas without going through a liquid phase).

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**Author:** ![Chas.E](https://avatars.discourse-cdn.com/v4/letter/c/e99b99/32.png) [@Chas.E](https://boards.straightdope.com/u/Chas.E)\
**Post date:** [July 27, 2001, 4:58pm UTC](https://boards.straightdope.com/t/how-fast-does-dry-ice-melt/73981/3 "2001-07-27T16:58:33Z")

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Nitpick: Dry ice doesn’t “melt,” it sublimes. It turns directly from solid to gas, which isn’t really considered melting. Dry ice evaporates rather than melts.  
I have a dry-ice sublimation calculating slide rule that I got from my grandfather, it was used in the olden days when rail cars were packed with dry ice to keep them cool. I’ll go dig it up and see what I can figure out about your query.

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**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\
**Post date:** [July 27, 2001, 5:42pm UTC](https://boards.straightdope.com/t/how-fast-does-dry-ice-melt/73981/4 "2001-07-27T17:42:28Z")

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A ~2X10X10" block will take several hours to sublimate at room temp. If it’s humid out the block will pull moisture from the air and give itself a bit of insulation.