CHECAL Flashcards
(12 cards)
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
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
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
c. 17600
a. 2400
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
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%
Fresh air containing 4 mol% water vapor is to be cooled and
dehumidified to a water content of 1.70 mol% H2O. A stream of
fresh air is combined with a recycle stream of previously
dehumidified air and passed through the cooler. The blended
stream entering the unit contains 2.3 mol% H2O. In the air
conditioner, some of the water in the feed stream is condensed
and removed as liquid. A fraction of the dehumidified air leaving
the cooler is recycled and the remainder is delivered to a room.
Taking 100 mol of dehumidified air delivered to the room as a
basis of calculation,
calculate the following:
The moles of fresh feed
a. 115 mol c. 102 mol
b. 126 mol d. 133 mol
c. 102 mol
The synthesis of ammonia proceeds according to the following
reaction:
N2 + 3 H2 —> 2 NH3
In a given plant, 4202 lb of nitrogen and 1046 lb of hydrogen are
fed to the synthesis reactor per hour. Production of pure ammonia
from this reactor is 3060 lb per hour.
- What is the limiting reactant?
a. N2 c. both (a) and (b)
b. H2 d. NH3 - What is the percent excess reactant?
a. 13% c. 17%
b. 16% d. 19% - What is the percent conversion obtained based on the limiting
reactant?
a. 50% c. 70%
b. 60% d. 80%
a. N2
b. 16%
b. 60%
Acrylonitrile is produced in the reaction of propylene, ammonia
and oxygen: C3H6 + NH3 + 3/2 O2 à C3H3N + 3 H2O
The feed contains 10 mole % propylene, 12 mole% ammonia,
and 78% air. A fractional conversion of 30% of the limiting
reactant is achieved. Taking 100 mol of feed as basis, determine
the following:
- The percentage by which of the reactants in excess
a. 24%, 6.2% c. 25%, 8.5%
b. 28%, 7.5% d. 20%, 9.2% - The mole% of water in the product gas
a. 6% c. 5%
b. 7% d. 9%
d. 20%, 9.2%
d. 9%
Propane is dehydrogenated to form propylene in a catalytic
reactor. The process is to be designed for a 95% overall
conversion of propane. The reaction products are separated into
two streams: the first, which contains H2, C3H6, and 0.555% of the
propane that leaves the reactor, is taken off as a product; the
second stream, which contains the balance of the unreacted
propane and 5% of the propylene in the first stream, is recycled
to the reactor.
- Calculate the ratio of moles recycled / mole fresh feed
a. 1.2 c. 2.5
b. 6.8 D. 9.0 - What is the single-pass conversion?
a. 9.6% c. 25.0%
b. 13.5% d. 38.2%
D. 9.0
a. 9.6%
A pure saturated hydrocarbon is burnt with excess air. Orsat
analysis of the stack gas shows 7.9% CO2, 1.18% CO, 0.24% H2,
5.25% O2, and 85.43% N2. Air is substantially dry. The stack
gases leave at 750 mmHg pressure.
Calculate:
66. The % excess air
a. 25% c 18%
b. 34% d. 44%
- The formula of the hydrocarbon
a. CH4 c C3H8
b. C2H6 d. C4H10
a. 25%
a. CH4
Orsat analysis of the stack gas from the combustion of a gaseous
mixture of acetylene and methane shows 9.82% CO2, 1.37%CO,
0.69% H2, 5.43% O2 and 82.69% N2.
Determine:
64. The % excess air
a. 15% c 10%
b. 20% d. 25%
- The % mol CH4 in the gaseous fuel
a. 50% c. 40%
b. 30% d. 60%
d. 25%
d. 60%
A furnace burns coal with the following analysis: M – 4.1%, VCM
– 24%, FC – 63.0%, N – 1.20%, S – 1.80%, Ash – 8.90%. The
refuse analyzed 4.8% VCM, 12.6% FC, 82.6% ash and a calorific
value of 32 MJ/kg. Calculate the percentage of gross calorific
value lost in the refuse.
a. 1.38% c. 0.90%
b. 2.16% d. 3.05%
b. 2.16%
