Do all substances have three different states of matter? For example, can a limestone rock exist as a solid, liquid, and gas at different temperatures? Does it, theoretically, have a triple point diagram?

1 Answer
May 21, 2016

Answer:

You can draw phase diagrams for most substances, but the materials in each phase aren’t necessarily the same substance.

Explanation:

For example, the phase diagram of limestone (calcium carbonate) is shown below.

i.stack.imgur.com

At 1 bar, calcium carbonate decomposes to CaO and CO2 at 898 °C.

As pressure increases, the temperature required for the decomposition increases until, at above 80 bar, the decomposition stops altogether.

Instead, we have an equilibrium mixture of solid and liquid calcium carbonate.