Phase Diagrams SOLID LIQUID GAS Critical Point Triple Point vaporizationcondensation sublimation deposition melting freezing
Critical point: Temperature and pressure beyond which it is impossible to condense the vapor into a liquid Triple point: Temperature and pressure at which all three phases coexist Normal boiling point: Temperature at which a liquid will boil under 1 atm of external pressure Normal freezing point: Temperature at which a liquid will freeze under 1 atm of external pressure What are the normal boiling and freezing points of water in C? Normal BP: 100 C Normal FP: 0 C
Temperature ( C) Pressure (atm) Phase Diagram for Carbon Dioxide Why is it not possible to have liquid CO 2 at atmospheric pressure? Because CO 2 won’t condense at pressures below 5.11 atm.
1.00 atm 0C0C 100 C Q: In terms of IMF’s, why is water’s phase diagram so different from the phase diagram for CO 2 ? CO 2 H2OH2O A: There is intermolecular hydrogen bonding present in water, but only LDFs in CO 2. Therefore, it takes more energy to separate water molecules from each other.
Temperature (°C) Heating curve of water solid warming solid + liquid present liquid warming liquid + gas present Gas warming Heat (kJ/s)
Temperature (°C) Heating curve of water melting/freezing point boiling/condensation point Temperature is constant during phase transitions!! All heat energy goes to changing the state of matter. Heat (kJ/s)
Heat (J) Temperature ( C) Heating Curve of Water vs. Methanol Reduction in polarity (1.85 D → 1.70 D) results in a dramatic change in physical properties D 1.70 D