Dr. Lamm
Supplemental Instruction
Iowa State University / Leader: / Shawn V.
Course: / CH E 210
Instructor: / Dr. Lamm
Date: / 3-9-2016
Practice Problems
An aqueous solution of sodium hydroxide is fed to a crystallizer. The crystallizer produces crystal hydrates of NaOH*2H2O. A product stream emerges containing the crystal and aqueous solution of sodium hydroxide in equilibrium. Two technicians take samples of the feed and product stream aqueous solutions. The first technician takes a 10 g sample of the feed and titrates the sample using 35 mL of 0.5 M sulfuric acid. The second technician takes a 10 g sample of the aqueous product solution and titrates the sample using 20 mL of 0.5 M sulfuric acid. The crystallizer evaporates 15 percent of the water (by mass) in the aqueous feed stream. Determine the rate of evaporation in the crystallizer. (Hint: M.W. of NaOH = 40 g/mol)
Why might it be important to find the evaporation rate of water?
Benzene is used to extract aqueous acetic acid at 30 degrees Celsius. The distribution coefficient for the extraction of aqueous acetic acid into benzene is 0.098. Consider a one-stage extraction system in which benzene is completely immiscible with water. The extractor is fed 1000 kg/hr of aqueous acetic acid at 20 wt%. The extractor is fed 100 kg/hr of benzene. Find the mass of acetone that leaves the extract-phase and the raffinate-phase.
Think of as many ways as you can to obtain more acetone in the extract.
Air at 80 degrees Celsius and atmospheric pressure contains 12 mol% water. A continuous stream of air enters a condenser, in which the temperature is lowered to 15 degrees Celsius and the pressure is raised to 4.0 atm (absolute). The air leaving the condenser is then heated isobarically to 100 degrees Celsius. Calculate the fraction of water that is condensed from the air and the relative humidity of the air at 100 degrees Celsius.
A stream of air flows into a mixer flowing at a rate of 500 L/hr at 100 degrees Celsius and 15 atm (gauge). The air is mixed with carbon dioxide that flows at 40 SCMH at 100 degrees Celsius and 20 atm (gauge). Calculate the mole fraction of carbon dioxide in the product stream.