Indian Olympiad Qualifier in Chemistry (IOQC) 2021-2022
conducted jointly by
Homi Bhabha Centre for Science Education (HBCSE-TIFR)
and
Association of Chemistry Teachers (ACT)
Part II: Indian National Chemistry Olympiad (INChO)
Homi Bhabha Centre for Science Education (HBCSE-TIFR)
Total 89 marks Time- 2 hours
Roll No.
Write your Roll No. at the space provided above.
This question booklet consists of 12 printed sheets including periodic table. Check that the booklet has
all the pages. If not, report to the invigilator immediately.
You must show the main steps in the calculations and state the necessary assumptions wherever
applicable.
Answers written in pencil will be penalized.
Use of non-programmable scientific calculator is allowed.
A copy of the Periodic Table of the Elements is provided at the end.
Do not leave the examination room until you are directed to do so.
The answer sheet must be returned to the invigilator. You can carry this question paper with you.
Fundamental Constants
Avogadro number NA = 6.022 × 1023 mol1 1 atm = 101325 Pa
Molar gas constant R = 8.314 J K–1 mol1 Density of water = 1000 kg m3
= 0.08205 L atm K−1 mol−1
pH = log [H+] pKa = log Ka
Enthalpy of combustion of ethanol = - 1371 kJ mol−1
Saturation vapour pressure of ethanol at 298 K = 0.08 atm
For air, γ = Cp/Cv = 1.4
, Problem 1 20 marks
A journey into epoxy resins
Epoxy resins are a versatile group of chemicals used in many industrial applications, particularly due to their
strong adhesive qualities, and stability under conditions such as high temperature, high humidity, and corrosive
environments.
Several resin based materials are in use, whose molecular level structure can be represented as shown in figure
1. It has high molar mass molecules (shown by bold lines) which may be monomeric, polymeric, or mixed
condensation products of two or more compounds. The molecules are held together with various crosslinking
chains (shown by grey solid lines) and/or non-bonding interactions such as charged interaction, van-der Waals
forces (shown by dashed lines). Depending on the packing of resin molecules, there may be pore spaces
between the molecules. Further there may be additional molecules or ions which may be trapped in this
structure during the material production process.
Resin Molecules
Other trapped
molecules
Figure 1: Model of a resin material
Properties of resinous materials depend on the nature of interactions between
resin molecules (cross-links and non-bonding interactions), and their interactions
with the trapped molecules. Sometimes interactions among the trapped molecules
also may significantly affect the material properties.
One commonly known example of a commercial epoxy resin is supplied in a
syringe/ tube containing a plunger and two compartments as shown in the figure
2. When the liquids present in these syringes are mixed, they condense together
to produce resin.
Often, one syringe compartment contains epichlorohydrin (2 molar equivalent)
and the other compartment is filled with Bisphenol A (1 molar equivalent) and
NaOH (less than 2 molar equivalent).
Figure 2: Commercial
tube of an epoxy resin
Page 2 of 11
conducted jointly by
Homi Bhabha Centre for Science Education (HBCSE-TIFR)
and
Association of Chemistry Teachers (ACT)
Part II: Indian National Chemistry Olympiad (INChO)
Homi Bhabha Centre for Science Education (HBCSE-TIFR)
Total 89 marks Time- 2 hours
Roll No.
Write your Roll No. at the space provided above.
This question booklet consists of 12 printed sheets including periodic table. Check that the booklet has
all the pages. If not, report to the invigilator immediately.
You must show the main steps in the calculations and state the necessary assumptions wherever
applicable.
Answers written in pencil will be penalized.
Use of non-programmable scientific calculator is allowed.
A copy of the Periodic Table of the Elements is provided at the end.
Do not leave the examination room until you are directed to do so.
The answer sheet must be returned to the invigilator. You can carry this question paper with you.
Fundamental Constants
Avogadro number NA = 6.022 × 1023 mol1 1 atm = 101325 Pa
Molar gas constant R = 8.314 J K–1 mol1 Density of water = 1000 kg m3
= 0.08205 L atm K−1 mol−1
pH = log [H+] pKa = log Ka
Enthalpy of combustion of ethanol = - 1371 kJ mol−1
Saturation vapour pressure of ethanol at 298 K = 0.08 atm
For air, γ = Cp/Cv = 1.4
, Problem 1 20 marks
A journey into epoxy resins
Epoxy resins are a versatile group of chemicals used in many industrial applications, particularly due to their
strong adhesive qualities, and stability under conditions such as high temperature, high humidity, and corrosive
environments.
Several resin based materials are in use, whose molecular level structure can be represented as shown in figure
1. It has high molar mass molecules (shown by bold lines) which may be monomeric, polymeric, or mixed
condensation products of two or more compounds. The molecules are held together with various crosslinking
chains (shown by grey solid lines) and/or non-bonding interactions such as charged interaction, van-der Waals
forces (shown by dashed lines). Depending on the packing of resin molecules, there may be pore spaces
between the molecules. Further there may be additional molecules or ions which may be trapped in this
structure during the material production process.
Resin Molecules
Other trapped
molecules
Figure 1: Model of a resin material
Properties of resinous materials depend on the nature of interactions between
resin molecules (cross-links and non-bonding interactions), and their interactions
with the trapped molecules. Sometimes interactions among the trapped molecules
also may significantly affect the material properties.
One commonly known example of a commercial epoxy resin is supplied in a
syringe/ tube containing a plunger and two compartments as shown in the figure
2. When the liquids present in these syringes are mixed, they condense together
to produce resin.
Often, one syringe compartment contains epichlorohydrin (2 molar equivalent)
and the other compartment is filled with Bisphenol A (1 molar equivalent) and
NaOH (less than 2 molar equivalent).
Figure 2: Commercial
tube of an epoxy resin
Page 2 of 11
