LearnChemE

#### Fugacity of a Single Component: Example Problems

Try to solve these problems before watching the solutions in the screencasts.

##### Example Problem 1

a) Calculate the fugacity of a pure gas at 500 K and 30 bar.
b) Suppose pure liquid is in equlibrium with the gas at 500 K and 30 bar. Calculate the fugacity.
c) Calculate the liquid fugacity at 500 K and 60 bar.
Vliq = 25 cm3/mol
Compressibility factor of gas: z = 1.0 – 0.01P

##### Example Problem 2

Use steam tables to calculate the fugacity of water at 250℃ and 2.5-MPa pressure.

An additional fugacity calculation problem can be found here.

Try to explain why the statements below are true.

• When 0.9 L of water is poured into a 1.0-L canning jar, which is then sealed and put into boiling water, the jar will reach equilibrium with the fugacity of water in the liquid equal to the fugacity of water in the gas phase at the top of the jar. The concentration of water in the liquid, however, will be orders of magnitude higher in the liquid phase than in the gas phase.
• When a wet shirt is hung outside to dry, the shirt dries quickly in Colorado because the fugacity of water in the shirt is higher than the fugacity of water in the air. In Alabama, the fugacity of water in the shirt is closer to the fugacity of water in the air so a wet shirt dries more slowly.
• Snow on the ground in the winter in Colorado often sublimes into the air (instead of melting) because the fugacity of water in the snow is much higher than the fugacity of water in the atmosphere.
• A glass with water and a glass with NaCl salt are placed on a table in Colorado. Months later, all the water had evaporated but the salt was essentially unchanged because the fugacity of water at room temperature is more than 20 orders of magnitude higher than the fugacity of NaCl at room temperature.