CHEM CALC Flashcards
Wine making involves a series of very complex reactions most of
which are performed by microorganisms. The starting
concentration of sugars determines the final alcohol content and
sweetness of the wine. The specific gravity of the starting stock
is therefore adjusted to achieve desired quality of wine. A starting
stock solution has a specific gravity of 1.075 and contains 12.7
wt% sugar. If all the sugar is assumed to be C12H22O11, determine
- kg sugar / kg H2O
a. 0.286 c. 0.145
b. 0.039 d. 0.327 - lb solution / ft3 solution
a. 67.1 c. 50.5
b. 39.2 d. 48.6 - g sugar / L solution
a. 202 c. 295
b. 136 d. 144
- C. 0.145
- A. 67.1
- B. 136
Two aqueous sulfuric acid solutions containing 20 wt% H2SO4
(SG=1.139) and 60 wt% H2SO4 (SG=1.498) are mixed to form a
4 M solution (SG=1.213).
- Calculate the mass fraction of sulfuric acid in the product solution.
a. 0.105 c. 0.323
b. 0.667 d. 0.548 - Calculate the feed ratio (liters 20% solution per liter 60% solution)
a. 2.96 c. 1.75
b. 3.08 d. 4.51 - What feed rate of the 60% solution (L/hr) would be required to
produce 1250 kg/h of the product.
a. 986 L/h c. 110 L/h
b. 257 L/h d. 462 L/h
- C. 0.323
- A. 2.96
- B. 257 L/h
If 1 L of ethyl alcohol is mixed with 1 L of water at 200C.
- How many kilograms of solution result?
a. 1.85 kg c. 1.79 kg
b. 2.06 kg d. 2.11 kg - How many liters?
a. 1.93 L c. 2.00 L
b. 1.88 L d. 2.15 L
- C. 1.79 kg
- A. 1.93 L
Air is bubbled through a drum of liquid hexane at a rate of 0.10
kmol/min. The gas stream leaving the drum contains 10 mol%
hexane vapor. Air may be considered insoluble in liquid hexane.
Use an integral balance to estimate the time required to vaporize
10 m3 of the liquid.
a. 4200 min c. 7700 min
b. 6900 min d. 8100 min
B. 6900 min
Urea, phosphoric acid and potassium chloride are mixed together
to obtain a mixed fertilizer having NPK content 10:26:26 as %N,
%P2O5 and %K2O by weight, balance being the weight of filler
materials. Calculate the amount of potassium chloride to be
mixed to get 1000 kg of mixed fertilizer.
a. 214.4 kg c. 411.5 kg
b. 359 kg d. 505 kg
C. 411.5 kg
A supplier shipped a material for chicken feed with the following
analytical report: protein – 22%, triglyceride – 8%, moisture –
10%. During transport moisture was picked up by the material;
the later analytical report showed 14% moisture. Based on the
latest report, recalculate the % triglyceride.
a. 21.02% c. 7.64%
b. 39.33% d. 14.65%
C. 7.64%
An evaporator is fed continuously with 25 MT/h of a solution
consisting of 10% NaOH, 10% NaCl, and 80% H2O. During
evaporation, water is boiled off, and salt precipitates as crystals,
which are settled and removed from the remaining liquor. The
concentrated liquor leaving the evaporator contains 50% NaOH,
2% NaCl and 48% H2O.
- Calculate the kg of water evaporated per hour
a. 19300 c. 17600
b. 18500 d. 16200 - Calculate the kg salt precipitated per hour
a. 2400 c. 1100
b. 3500 d. 4700 - Calculate the kg of concentrated liquor produced per hour
a. 4000 c. 6000
b. 3000 d. 5000
- C. 17600
- A. 2400
- D. 5000
An experimental oil is used to distil 6000 kg/hr of Athabasta tar sand which analyzes 30% “heavy oil”, “light oil”, and non-volatile matter. If the distillate contains 12% heavy oil and this constitutes 25% recovery of the component the weight in kg of the distillate obtained is.
3750 kg/hr
Ten kilograms each of salts A and B are dissolved in 50 kg of
water. The solubility of A in water is 1 kg per kg water and that of
B is 0.5 kg per kg of water. The solution is heated to evaporate water. When the concentration of the solution reaches the
saturation concentration of any salt, further evaporation results in
the crystallization of that salt. If 70% of the water that is originally
present in the solution is driven off by evaporation, determine the
following:
- The weight of the final solution
a. 46.5 c. 11.5
b. 28.5 d. 32.5 - The weight of the crystals formed
a. 2.5 c. 0
b. 5.5 d.1.5
- D. 32.5
- A. 2.5
1200 lb of barium nitrate is dissolved in sufficient water to form a
saturated solution at 900C. Assuming that 5% of the weight of the
original solution is lost through evaporation calculate the crop of
crystals obtained when cooled at 200C. Solubility data for barium
nitrate at 900C is 30.6% wt and 8.6 wt% at 200C.
a. 952.4 lbs c. 962.4 lbs
b. 970 lbs d. 980 lbs
C. 962.4 lbs
What is the theoretical yield of crystals which may be obtained by
cooling a solution containing 1000 kg of sodium sulfate (mw = 142
kg/kmol) in 5000 kg water to 283 K? The solubility of sodium
sulfate at 283 K is 9 kg anhydrous salt / 100 kg water and the
deposited crystals will consist of decahydrate. It may be assumed
that 2% of the water will be lost by evaporation during cooling.
a. 4469.17 kg c. 6000 kg
b. 250 kg d. 1430.83 kg
D. 1430.83 kg
A solution of NH4Cl is saturated at 700C. Calculate the
temperature to which this solution must be cooled in order to
crystallize out of 45% of the NH4Cl. The solubility of NH4Cl in
water are:
Temperature, 0C Solubility,
g/100g H2O
70 60.2
10 33.3
0 29.4
a. 8.6 c. 9.5
b. 5.7 d. 7.2
C. 9.5
In the azeotropic distillation of an ethanol–water solution, a feed
mixture containing 95.6% alcohol is mixed with pure benzene and
distilled. The benzene forms a ternary azeotrope with alcohol–
water with a composition of 74.1% benzene, 7.4% water and
18.5% alcohol, which is distilled over as the overhead product.
Absolute alcohol is obtained as the residue product. Determine
the quantity of benzene required for producing 100 kg of absolute
alcohol.
a. 48 kg c. 66 kg
b. 74 kg d. 52 kg
D. 52 kg
Oil is extracted from seeds by leaching with organic solvents.
Soybean seeds containing 20% oil, 65% inert solids and 15%
water are leached with hexane and after extraction the solid
residue is removed from the solution of oil in hexane. The residue
analyzed 1.0% oil, 88% inert cake and 11% water. What percent
of oil is recovered?
a. 90% c. 96%
b. 82% d. 87%
C. 96%
Acetone is recovered from an acetone-air mixture containing 25%
(volume) acetone by scrubbing with water. Assuming that air is
insoluble in water, determine the percent of acetone in the entering gas that is absorbed if the gas leaving the scrubber
analyzes 5% acetone.
a. 96% c. 65%
b. 84% d. 73%
B. 84%
One hundred pounds of solution containing 80 wt% Na2SO4 must
be obtained by evaporating a dilute solution using a double effect
evaporator. If the evaporator from the 2nd effect is 60% of that
coming from the first effect and the concentrate of the first effect
contains 1 lb Na2SO4 per pound of water. Calculate for the
composition of the feed.
a. 69% Na2SO4 c. 45% Na2SO4
b. 55% Na2SO4 d. 31% Na2SO4
D. 31% Na2SO4
One drier will dry a material from 45% moisture (wb) to 20%
moisture (db) from here the material enters another drier where
the H2O content is further reduced to give a final product weighing
1000 kg. If the total evaporation from both driers is 800 kg, the
moisture of the final product is
a. 5% c. 2%
b. 3% d. 1%
D. 1%