I love thermodynamics

I filled up a water bottle today, and that was my thought.

Allow me to elaborate, at length, and with no good reason. Then, if you’re good and comment, I might record an actually interesting series of events, which triggered responses such as, “Gasp!”, “Ha!”, and “Snore!” when recited to a captive audience over lunch today.

I refilled an Arrowhead .5 L disposable water bottle. It has been on my desk, closed, for a couple of days, so I rinsed it with hot water, first, then put in cold. It was wonderful. Why?

I knew the hot water, while not boiling, was hot enough to cause air in the water bottle to expand — I put in maybe four tablespoons of water, put the cap on, then swished the water around. The bottle grew warm to the touch, and unscrewing the cap caused an audible hiss. I poured out the water, and put in a roughly equal amount of cold water. As I screwed the cap on, the bottle collapsed on itself due to the air condensing. Opening the water bottle caused equilibrium to rapidly reestablish, and the bottle regained its original form.

Now, isn’t thermodynamics cool?