PHASE DIAGRAMS

Phase Diagram for Water

1.  Study the phase diagram of water.  What two units are plotted against each other in a phase diagram graph?

2.  Give the state or states of matter present at each of the following conditions:

(A) 100 oC and 1 atm ___________________                    (F) 150 oC and 200 atm ___________________

(B) 0 oC and 1 atm ___________________                       (G) 400 oC and 220 atm ___________________

(C) 100 oC and 218.3 atm ___________________             (H) 375 oC and 230 atm ___________________

(D) 50 oC and 1 atm ___________________                     (I) -50 oC and 0.003 atm __________________
(E) 50 oC and 0.0060 atm ___________________ (J) 0.01 oC and 0.006 atm _______________

3.  After a substance passes a certain temperature (critical temperature), it cannot be liquefied.  Regardless of the amount of pressure applied, the substance will remain a gas.  What is the critical temperature of water?

Define critical temperature:

4.  When a substance reaches its critical temperature, it can be liquefied if enough pressure is applied.  The pressure necessary to do this is called critical pressure.  What is the critical pressure of water?

Define critical pressure:

5.  Give the temperature and pressure for the triple point of water.

6.  What unique condition occurs at the triple point?

PHASE DIAGRAM FOR CARBON DIOXIDE

1.  Label the following on the phase diagram:  critical temperature, critical pressure, triple point, sublimation line, freezing/melting point line, boiling point line

2.
What are the critical temperature and critical pressure of carbon dioxide?

3.  What is the triple point of carbon dioxide?

4.  Identify the state or states of matter that CO2 would exist under the following conditions:
(A) -78.5 oC and 1 atm ___________________

(B) -80 oC and 2 atm ___________________

(C) -40 oC and 6 atm ___________________

(D) 32 oC and 75 atm ___________________

(E) STP conditions _________________

5.  Can CO2 ever be a liquid at room temperature?  Explain why or why not.

6.  When dry ice (solid carbon dioxide) is exposed to room temperature conditions, what process describes its phase change?  How does the phase diagram explain why CO2 does not "melt"?

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