work #2: Liquids, Solids, and Intermolecular Forces . Use the phase diagram of c
ID: 579087 • Letter: W
Question
work #2: Liquids, Solids, and Intermolecular Forces . Use the phase diagram of carbon dioxide, co, shown below to answer the questions that follow. 7380.01 t .. . Solid iquid 0 6701 : Gas 510.2... a. 101.4-. 194.7 2168 298.2 304.2 Temperature (K) a. What is the phase of CO; at 2.0 atm and -100*C? What process occurs when the pressure applied on a sample of CO2 at-75.6'C and 3.0 atm is decreased to 0.50 atm? b. c. At what temperature and pressure does solid, liquid, and gas exist at equilibrium? d. Provide a temperature and pressure at which CO2 boils. e. Provide a temperature and pressure at which deposition occurs. f. Provide the temperature and pressure of the critical point.Explanation / Answer
a.
Convert pressure in kPa
Pressure = 2.0 atm
Use conversion factor (101.325 kPa / 1 atm)
Pressure = 2.0 atm x (101.325 kPa / 1 atm)
Pressure = 202.65 atm
Convert temperature in Kelvin (K)
Temperature = -100oC
Add 273 to convert into kelvin
Temperature = (-100 + 273) K
Temperature = 173 K
Find the point in phase diagram where pressure is 202.65 atm and temperature is 173 K.
This point is in solid phase. Therefore, phase of CO2 at 2.0 atm and -100oC is Solid.
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b.
Find the point in phase diagram where temperature is -75.6oC and pressure is 3.0 atm.
Convert pressure into kPa.
Pressure = 3.0 atm
Use conversion factor (101.325 kPa / 1 atm)
Pressure = 3.0 atm x (101.325 kPa / 1 atm)
Pressure = 303.975 atm
Convert temperature in Kelvin (K)
Temperature = - 75.6 oC
Add 273 to convert into kelvin
Temperature = (- 75.6 + 273) K
Temperature = 197.4 K
Pressure is decreased to 0.50 atm. Convert pressure into kPa
Pressure = 0.5 atm
Use conversion factor (101.325 kPa / 1 atm)
Pressure = 0.5 atm x (101.325 kPa / 1 atm)
Pressure = 50.662 atm
Therefore, at 197.4 K, pressure is reduced from 303.975 atm to 50.662 atm
According to phase diagram, at 303.975 atm and 197.4 K, CO2 is in solid phase. Decrease in pressure to 50.662 atm results in change in phase of CO2 from solid to gaseous phase.
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c.
The temperature and pressure at which solid, liquid and gas exists in equilibrium is called as triple point. From the phase diagram it can be seen that, at 510.2 kPa and 216.8 K, all the three phases exists in equilibrium.
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d.
During boiling, CO2 is in equilibrium between liquid phase and gas phase. Therefore, at any point on liquid-gas equilibrium line CO2 will start boiling. One such point given in phase diagram is pressure of 6701.7 kPa and temperature of 298.2 K
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e.
Deposition is the reverse of sublimation. During deposition gas is converted into solid. Therefore, at any point on solid-gas equilibrium line, deposition of CO2 takes place. One such point given in phase diagram is pressure of 101.4 kPa and temperature of 194.7 K.
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f.
Critical point is the point at which phase diagram end. Critical point in given phase diagram is pressure of 7380.0 kPa and temperature of 304.2 K.
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