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Hey Ray: Popping ice

Hey Ray: Popping Ice Cubes
Hey Ray: Popping Ice Cubes 03:00

PITTSBURGH (KDKA) - It is time to tackle another viewer question! Greg asks:

Hey Ray!

When I put some ice cubes from the ice tray in my glass that has ice tea or water, the cube will explode! There have been times that liquid comes flying out of the glass. Why would an ice cube explode? 

Thanks, Greg

Greg's got some cracked ice! Greg from Finleyville

This is probably something you have noticed with ice cubes from the ice tray. When you drop them in a liquid, especially a hot liquid, they crack, pop, splinter, or sometimes explode!

First, let's talk about how weird water is.

One reason water is weird is that the water molecules start to contract as they cool.

According to the National Weather Service, as water's temperature decreases to 40°F, the molecules slow and contract, and the density increases, the same as most other substances. 

Below 40°F though, the water molecules begin to bond to each other. As that happens, they are held apart, and the water expands again, decreasing the density. At 32°F (0°C), all molecules are locked into a crystalline structure, you know ice crystals, resulting in a nine percent expansion in size. 

This expansion and the corresponding decrease in density is the reason ice floats.

Ice, ice...Ray-bee? Getty Images

This however does not answer Greg's question. It just gives us some clues. 

So what is happening?

Ice cubes in a tray! Ray Petelin

In Greg's case, the key was that he was using ice cubes from an ice cube tray. Often times hard water minerals build up in an ice cube tray. 

Water molecules and ice crystals can form on these minerals, and this creates tiny imperfections in the ice. Scratches in the ice cube tray from aggressive cleaning can create these imperfections, too.

So now you have a seemingly normal ice cube but with tiny imperfections. Imperfections that are actually weak spots in a solid structure!

See - there are some imperfections! Ray Petelin

When you toss the ice cube into a liquid that is not frozen, you rapidly start to change the temperature of the ice cube. 

The temperature change happens on the outside of the cube, while the inside stays frozen. That rapid change in temperature causes a contraction of the ice, especially the outer layer. The imperfections or weak spots of the ice are forced to crack at this point. 

If these events happen fast enough, sometimes the ice will even have what seems like a mini explosion.

It's like a mini explosion! Ray Petelin

Gently cleaning the minerals out with vinegar will help remove some of those imperfections.  

Just rinse it well after cleaning, so your drink doesn't taste like vinegar.  

That would probably be worse than popping ice!

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