Can water in a pressurised contained, which does not allow for the liquid to expand, heat up?
In: Chemistry
Liquids are usually considered incompressible, but that’s technically not true. They are compressible, it just takes so much pressure that we don’t notice. So if you put 4°C water (a its densest point) and put it into an infinitely strong container with no airbubbles, you could heat it up without having the water expand – but the pressure would be extremely high.
This is exactly what a pressure cooker does. Normally, water boils at 100 degrees celsius. With added pressure, it will boil at 120 degrees or even higher, allow for much quicker cooking temperatures.
[https://www.engineeringtoolbox.com/boiling-point-water-d_926.html](https://www.engineeringtoolbox.com/boiling-point-water-d_926.html)
Here you can find graphs that plot boiling temperature to pressure. Yes, it is possible to heat, it just takes higher temperatures to reach boiling point, because the gas has to stay in a smaller space.
Normally when water is heated, the pressure stays normal, the volume increases, and the temperature goes up.
When water is contained, the volume can’t increase. So when water is heated, it wants to expand but it can’t. The water pushes against the walls of the container and the pressure increases.
So yes the water can heat up, the pressure increases instead of the volume.
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