Republic of the Philippines
BATANGAS STATE UNIVERSITY
The National Engineering University
Alangilan Campus
Golden Country Homes, Alangilan Batangas City, Batangas, Philippines 4200
Tel Nos.: (+63 43) 425-0139 local 2121 / 2221
E-mail Address: coe.alangilan@g.batstate-u.edu.ph | Website Address: http://www.batstate-u.edu.ph
College of Engineering - Department of Chemical Engineering
Instructions: Answer the following problems in a long bond paper, (APPROPRIATE LETTERHEAD OF THE UNIVERSITY
SHALL BE USED) with a 1" margin on all sides. Make sure that SOLUTIONS are WRITTEN LEGIBLY with a BLACK/BLUE
INK and FINAL ANSWERS were BOXED. All solutions are to be handed FACE-TO-FACE or be left in 4TH FLOOR FACULTY
ROOM, CEAFA BLDG.
Be reminded that FAILURE TO SUBMIT it on time will automatically credit a final grade of INC or 5.00 for ChE 414
– Separation Processes.
Note: Problems may be printed with TIMES NEW ROMAN as its FONT STYLE, and FONT SIZE of 12.
1. Benzoic acid is 9 times more soluble in chloroform than in water. Determine the percent benzoic acid that will remain
from a water solution of benzoic acid if extraction as in (A) were followed by an extraction as in (B). (5 PTS)
2. An original mixture weighing 100 kg and containing 30 kg of isopropyl ether (𝐶), 10 kg of acetic acid (𝐴), and 60
kg water (𝐵) is equilibriated and the equilibrium phases separated. What are the compositions of the two equilibrium
phases? (10 PTS)
3. The compositions of the two equilibrium layers in the previous number are for the extract layer (𝑉) 𝑦𝐴 = 0.04, 𝑦𝐵 =
0.02, and 𝑦𝐶 = 0.94, and for the raffinate layer layer (𝐿) 𝑥𝐴 = 0.12, 𝑥𝐵 = 0.86, and 𝑥𝐶 = 0.02. The original mixture
contained 100 kg and 𝑥𝐴𝑀 = 0.10. Determine the amounts of 𝑉 and 𝐿. (10 PTS)
4. Powdered limestone containing 10,000 ppm NaOH is to be washed in a two-step continuous counter-current leaching
system to remove most of the NaOH. Two stages and 10,000 liters of water per 10 MT/day of limestone feed are
used. The slurry discharged and removed from the underflow contains 0.091 MT of water per MT. Assuming
complete mixing and washing, calculate the NaOH content of the washed and dried limestone in ppm. (5 PTS)
5. Roasted copper ore containing the copper as CuSO4 is to be extracted in a countercurrent stage extractor. Each hour
a charge consisting of 10 tons of gangue, 1.2 tons of copper sulfate, and 0.5 ton of water is to be treated. The strong
liquor produced is consist of 90 percent water and 10 percent copper sulfate by weight. The recovery of copper sulfate
is to be 98 percent of that in the ore. Pure water is to be used as the fresh solvent. After each stage, 1 ton of inert
gangue retains 2 tons of water plus copper sulfate dissolved in that water. Equilibrium is attained in each stage. How
many stages are required? (5 PTS)
6. By extraction with kerosene, 2 tons of waxed paper per day is to be dewaxed in a continuous countercurrent extraction
system that contains a number of ideal stages. The waxed paper contains, by weight, 25% paraffin wax and 75%
paper pulp. The extracted pulp is put through a dryer to evaporate the kerosene. The pulp, which retains the
unextracted wax after evaporation, must not contain over 0.2 lb of wax per 100 lb of wax-free pulp. The kerosene
used for the extraction contains 0.05 lb of wax per 100 lb of wax free kerosene. Experiments show that the pulp
retains 2.0 lb of kerosene per lb of kerosene and wax-free pulp as it is transferred from cell to cell. The extract from
the battery is to contain 5 lb of wax per 100 lb of wax-free kerosene. How many stages are required? (5 PTS)
7. A copper ore is to be leached with water in a single stage 350 tons of copper ore containing 22% by mass copper
sulfate and 78% by mass insoluble inert is leached with 1000 tons of water. If inert will retain 1.5 tons of water per
ton inert, calculate the amount of resulting solution. (5 PTS)
8. In a single stage extraction, 10 kg of pure solvent S (containing no solute) is mixed with 30 kg of feed F containing
A at a mass fraction Xf = 0.2. The mixture splits into an extract phase E and a raffinate R, containing at X E = 0.5 and
XR = 0.05 respectively. Find the total mass of the extract phase. (5 PTS)
Prepared by:
Engr. Kim Dowell D. Panganiban
Instructor ChE 414 – Separation Process
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