Given the following phase diagram. Pressure (atm) Temperature (°C) Select the correct statement concerning this phase diagram. The dotted line represents compression and expansion of the compound at constant temperature. The line between regions A and C represents the conditions for the equilibrium between solid and liquid. According to this phase diagram, the solid of this compound will float in its liquid phase. Region A represents the conditions under which the substance is a solid.

18 19 20

Study the following phase diagram of Substance X. pressure (atm) 24 solid 100 liquid 200 temperature (K) Use this diagram to answer the following questions. a gas 300 Suppose a small sample of pure X is held at -12. °C and 12.0 atm. What will be the state of the sample? Suppose the temperature is held constant at -12. °C but the pressure is decreased by 6 atm. What will happen to the sample? Suppose a small sample of pure X is held at -12. °C and 12.0 atm. What will be the state of the sample? Suppose the temperature is held constant at -12. °C but the pressure is decreased by 6 atm. What will happen to the sample? Suppose, on the other hand, the pressure is held constant at 12.0 atm but the temperature is decreased by 116. °C. What will happen to the sample? (choose one) (choose one) (choose one) (choose one) (choose one)

- Suppose a small sample of pure X is held at  -236.°C and 2.0 atm. What will be the state of the sample (solid, liquid, or gas)? - Suppose the temperature is held constant at -236.°C but the pressure is decreased by 1.2 atm. What will happen to the sample (nothing, it will melt, it will freeze, it will boil, it will condense, it will sublime, or it will deposit)? - Suppose, on the other hand, the pressure is held constant at 2.0 atm but the temperature is increased by 137°C. What will happen to the sample (nothing, it will melt, it will freeze, it will boil, it will condense, it will sublime, or it will deposit)? All these are part of one question.

Substance X is known to exist at 1 atm in the solid, liquid, or vapor phase, depending on the temperature. Additionally, the values of these other properties of X I have been determined: melting point enthalpy of fusion temperature (°C) 120- 110- 100- 90- 80 70- 60- You may also assume X behaves as an ideal gas in the vapor phase. Suppose a small sample of X at 20 °C is put into an evacuated flask and heated at a constant rate until 10.0 kJ/mol of heat has been added to the sample. Graph the temperature of the sample that would be observed during this experiment. density 50+ 40 30- 20 65. °C 10.00 kJ/mol 3 2.80 g/cm³ (solid) 2.30 g/mL (liquid) 0 heat added (kJ/mol) 8 9 boiling point enthalpy of vaporization 10 heat capacity P 100. °C X 21.00 kJ/mol -1 38. J K mol (solid) 29. J.K¹ mol 48. J.K¹ mol 1 (liquid) (vapor) 2 00 ola Ar B

There are three sets of sketches below, showing the same pure molecular compound (water, molecular formula H₂O) at three different temperatures. The sketches are drawn as if a sample of water were under a microscope so powerful that individual atoms could be seen. Only one sketch in each set is correct. Use the slider to choose the correct sketch in each set. You may need the following information: melting point of H₂O: 0.0 °C boiling point of H₂O: 100.0 °C A (Choose one) (Choose one) 188. °C B 5 35. °C 4 5 (Choose one) -25. °℃

.  The vapor pressure and enthalpy of vaporization of an unknown substance are measured to be 479.6 torr and 35.3 kJ/mol, respectively at room temperature (298.15 K). Estimate the normal boiling point of the substance at an atmospheric pressure of 760 torr.

Draw the phase diagram of carbon dioxide and explain the meaning of three regions and lines.

The following compounds are liquid at -10 °C: diethyl ether, methanol, and ethylene glycol. Arrange the three compounds in order of increasing vapor pressure at -10 °C. Choose between 1 - lowest vapor pressure, 2, or 3 - highest vapor pressure. Note: Reference the Phase change properties of pure substances table for additional information. Ethylene glycol (Choose one) Methanol (Choose one) Diethyl ether (Choose one) G

Differentiate the structure of a crystalline solid and amorphous solid. Give example of their structure