Last modified: Sun 01/17/2016 06:53:16 pm
BCE

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Answer all of the questions below. If you do not know an answer enter CNA. However, it will help me the most if you answer each question with your best intuition/idea about what would be a reasonable answer.

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1. The equilibrium vapor pressure for water at 45 °C is 71.9 mmHg.

a) If the pressure due to water in the vapor phase in a container is 45.7 mmHg, what phase or phases are present in the container?

b) Can the pressure due to water in the vapor phase ever exceed 71.9 mmHg at 45 °C in a container?

Yes/No

Explain

4. Look at the table of vapor pressures at different temperatures and enter the eqilibrium vapor pressure for water at 85 °C and at 95 °C.

mmHg (85 °C)

mmHg (95 °C)

b) A sample of water in a container at 95 °C exerts a pressure of 580 mmHg. Explain why we can assume that the sample is only vapor/gas under these conditions of temperature and pressure.

c) If the container is cooled to 85 °C calculate the pressure exerted by the sample (use the ideal gas law P1/T1 = P2/T2) assuming the sample remains in the gas phase. Also assume the volume is held constant and no water is lost. (Watch out for the units on T, they must be Kelvin.)

mmHg

d) Based on you answer in Q1c and the equilibrium vapor pressure at 85 °C, indicate the phase(s) present in the container at 85 °C.

5) Solve the following : (Note: if the number is less than 1, like 3.356 x 10-3, enter the number as 3.356e-3.)

a) 1/298 =

b) ln (345/670) =

c) ln 345 - ln 670 =

d) ln (525/340) = - H/8.314 *(1/345 - 1/304)

H =

4. Given the following values in the Clausius-Clapyron equation solve for P2 (where P2 is the vapor pressure at T2) .

ln ( P2/330) = -(28,000 J mol-1/8.314 J mol-1K-1) * (1/313 K - 1/293 K)

mmHg

 

5. Is there anything about the questions that you feel you do not understand? List your concerns/questions.

6. If there is one question you would like to have answered in lecture, what would that question be?