Testing why Powerade Froze

An 8 pack of Powerade, a sports drink is in my refrigerator. They all chilled as per normal, however one froze solid. The cap was loose, I assume from the freeze expansion. Nothing else was frozen. What would cause this? Could the one have been tampered with?
- Tom (age 68)
San Antonio, Tx USA

There are some really different explanations possible here. We'll try some guesses. You could do some tests to check them.

It could be that the one bottle just happened to be closest to the spot where the cold air is blown into the fridge. If the fridge happened to be set cold, that could freeze the one bottle. I guess that could loosen the top. If that were what happened, then maybe you could reproduce the whole effect.

Another possibility, as you suspect, could be that somebody loosened the top and replaced the Powerade with something with a lower freezing point, e.g. pure water. Then if the temperature happened to be just between the freezing point of the water and that of the Powerade, only the water would freeze. You could try replacing a bottle of Powerade with one of water and see what happens. 

There are some aspects that seem stranger than even those ideas. Doesn't Powerade have food color in it? So you'd notice if it were replaced with water. If it were just partly replaced, then it would freeze until the liquid part was as concentrated as the original and then stop, not fully frozen.

Here's another possibility. That part of the fridge may have been too cold, say -5°C. Although that's below  the true freezing point, bottled drinks often can stay as supercooled liquids for a long time. (See  ) If one of the bottles happened to have some bit of dust in it (maybe because it had already been opened) it would start freezing more easily. Right after supercooled water starts to freeze, it turns to slush. If it sits a while cold, however, it can freeze solid. You could test whether bottles left at that spot in the fridge turn to slush if you shake them a bit to see if supercooling is happening.

Of course if you can get a good thermometer, you can back up the measurements by testing the temperature at various points in the fridge, taken with the door closed and reading the thermometer quickly after it's opened.

Mike W.

(published on 12/29/2013)

Thanks for the reply. Placement of the Powerades is always the same in refrigerator and this has never happened before. I moved the frozen one away from where it froze and nothing changed. I forgot to mention that it is grape flavor and the bottom 1/2 inch is grape color and the rest clear. The odor is the same as a regular bottle of grape Powerade.
- Anonymous

That does clear up one question. It looks like the solute including the purple food color did stay separate in what became a concentrated liquid at the bottom. That makes a lot of sense. It sounds like it was indeed the original Powerade that froze.

My guess is that the temperature was around -3°C or so in that whole portion of the fridge, and that one bottle for some reason didn't stay supercooled. A tiny speck of nucleation material, whether from the bottling plant or because the bottle was opened first, would account for that. Moving the bottle wouldn't melt it, because the frozen state would be the stable one at that temperature. The other bottles, lacking some nucleation site, just never got to that stable state.

Mike W.

 

(published on 12/30/2013)