|
Compression can cause a slight raise in temperature, and I mean slight. Perhaps the one that wasn't opened didn't freeze because as the water cooled and began to freeze, it expanded, causing a small degree of compression. The slight raise in temperature inside the bottle may been just enough to keep all of its contents from freezing. Outside conditions would have to be perfect for this to happen, i.e. the outside temperature just low enough to freeze it but not so low that it would overpower the slight rise in temp inside the bottle. So I wouldn't expect it to happen very often.
The open bottle would have had more room to expand, so it wouldn't have had any compression.
|