I'm not absolutely positively sure of this. I'm only about 99.5% sure.
I'm going to say that it's a chemical change.
Why ?
When a physical change occurs, the properties and characteristics of
the substance stay the same ... like crushing a rock, or boiling water.
In this experiment, you started with water. Water is a single substance,
and its boiling point is +100°C.
After the change, you suddenly have TWO substances.
Their boiling points are -183°C and -253°C .
It's plain to see that the characteristics and properties of the
new substances are nothing like the original substance.
Yep. I convinced myself. It's definitely a chemical change.
