The Phase Diagram

A phase diagram is a graphical representation of the change of matter from one phase (solid, liquid, gas) to another.

Consider compounds Ma and Mb.

The properties of Ma are as follows:
Melting pt. = 00C at normal conditions, 1 atm (101325Pa)
Boiling pt. = 1000C at normal conditions, 1 atm(101325Pa)
Critical Temperature = 3740C, at 218 atm
Triple pt. =0.00980C, at 0.006 atm (611Pa)

The properties of Mb are as follows:
Melting pt. = -78.50C at normal conditions, 1 atm (101,325Pa)
Boiling pt. = -570C at normal conditions, 1 atm (101,325Pa)
Critical Temperature = 31.10C, at 7.39MPa
Triple pt. =-56.60C, at 518kPa

(a) Determine the identity of Ma and Mb and sketch their respective phase diagrams
(b) What is the implication of the triple point pressure of Mb being above 1 atm?

The strings:

S7P5A51 (Change - Physical Change)

The math:
Pj Problem of Interest is of type change (Physical - Change).

(a) Compound Ma is water (H2O). The following is its phase diagram:

Compound Mb is carbon dioxide (CO2)

(b) Liquid carbon dioxide does not exist at 1atm pressure. So, the triple point pressure of carbon dioxide has to be above 1 atm in order for all three phases to exist in equilibrium.

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