Q And A

1. School of Chemical and Biotechnology
First CIA Test – Dec 2021
Course Code: CHY101
Course Name: Engineering Chemistry
Duration: 90 minutes Max Marks: 50
GENERAL INSTRUCTION
Start with writing your personnel details (Name, Register Number, Section, Name of the
faculty handling the course) on the first page.
PART A 10 X 2= 20 Marks
1. The steam boiler corrosion takes place due to dissolved gases in water. What are the
consequences of the use of sodium sulphite to trap one of the gases?
2. Ascertain the compound A and B based on the following observations. Both A and B
possess equal cation but different anions.
Compound
Solubility in EDTA
solution
Solubility in water at
high temperature
A Soluble
Precipitation without
degradation
B Soluble
Precipitation following
degradation
3. Speculate what will happen if chlorine gas is bubbled into a solution holding NaBr
together with NaI at 25 °C. Justify your answer. Presume all species exist in their standard
states.
𝐸 / = −1.396 𝑉
𝐸 / = −1.087 𝑉
𝐸 / = 0.5355 𝑉
4. In a titration experiment, 3.7 g of Na2EDTA was dissolved in 500 mL of distilled water.
The EDTA solution was filled in a burette and the initial reading was 20.0 mL. 150 mL
of sample water was titrated against the EDTA solution along with a few drops of
Eriochrome Black –T. The burette reading was 35.0 mL at the time of a colour change in
the above titration. Calculate the hardness of the sample water?
5. What should be the concentration of ions in the cathodic compartment in the below cell to
show non-spontaneity in either direction? Justify your answer.
Ag (s)│Ag+
(0.15 M) ║Hg2+
│Hg(l)
6. Elements with very low standard reduction potential are considered as weaker oxidizing
agents or stronger reducing agents. Justify the aforementioned statement with a suitable
example.
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2. 7. Zeolite (𝑁𝑎 𝑍) has exchangeable 𝑁𝑎 ions and we use the zeolite to exchange calcium
and magnesium ions present in hard water with the sodium ions. Why can’t we replace
the sodium ions (𝑁𝑎 𝑖𝑜𝑛𝑠) with protons (𝐻 𝑖𝑜𝑛𝑠) and use the zeolite as a cation
exchanger in the ion exchange process?
8. Out of the specified water origins, which one can be utilized as potable water without
further treatment? Justify your answer.
(i) A Himalayan stream emerging from a Glacier
(ii) Water from river Yamuna.
9. Imagine that you utilized a cation exchange resin alone to treat impure water. The hard
water contains calcium and magnesium chloride. The treated water is stored in a steel
container. What would be the expected the consequences associated with the treated
water?
10. A high-pressure boiler every day converts 10,000 L of water into high-velocity steam.
Predict the outcome if we add 5 kg of CaCO3 into the high-pressure boiler during the
generation of the high-velocity steam (Scenario I) (or) 5 kg of Na2CO3 added into the
high-pressure boiler during the generation of the high-velocity steam (Scenario II)
PART B 3 X 10 = 30 Marks
11. (a) A plywood industry uses boiler steam to make the plywood a very stronger and long-
lasting one. The company uses a zeolite softener before feeding the water into the boiler.
The machine has a capacity of 5000 L/hour to soften hard water. During a process, the
zeolite bed was exhausted after 10.5 hours and 425 litres of 0.6 N sodium chloride solution
was required to restart the function of the zeolite process. Work out the hardness of hard
water in ppm. (5)
(b) Magnesium chloride is one of many materials used for dust control, soil stabilization,
and wind deterioration softening. The leftover water from a MgCl2 production company
has been ceaselessly released into a river located nearby. Furthermore, an open-pit quarry
produces Gypsum and discharges the wastewater into the same river. In this context, will
you allow the river water directly to feed into a steam boiler? Defend your answer and
provide the approaches to remove these contaminants by appropriate treatment techniques
with proper equations. (5)
12. (a) For a hypothetical electrochemical cell represented by the following cell
diagram, 𝐴( )|𝐴𝑋 (𝑎𝑞, 0.25 𝑀)||𝐵𝑋 (𝑎𝑞, 1.25 𝑀)|𝐵( ), where 𝑋 is a monovalent anion,
calculate the cell potential. Given: 𝐸 / = 24 𝑚𝑉 and 𝐸 / = 42 𝑚𝑉. While diluting
the cathodic compartment, at which concentration does the cathodic compartment turns
to anodic compartment? (5)
(b) For the treatment of the brackish water containing considerable quantities of colloidal
impurities, which among the two methods of purification of brackish water would be more
suitable? Explain the working principle of the method and state how it will be more
suitable for the treatment of brackish water with colloidal impurities. (5)
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3. 13. You are provided with four containers (A-D) of impure water. You are assigned to purify
the water in each one of the given below containers by the “Zeolite process”. Predict the
challenges associated with the purification of the water in each one of the containers by
the zeolite process. Justify your answer with appropriate reasons and equations. Also,
appraise the advantages of the ion exchange process over the zeolite process in the
purification of the given below water containers.
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In the Answer Script,
 Number each page and sign on each page of the answer script.
 The parent or guardian must sign on each page of the answer script with the statement
‘Ethically compliant’
 All pages must be scanned in to a single pdf that should be named with the register
number of the candidate and should be uploaded as a single pdf in the google classroom
within 30 minutes of the scheduled close of the examination