International Junior Science Olympiad Theory Sample Question Paper 2017 : ijsoweb.org

Organisation : International Junior Science Olympiad
Exam : International Junior Science Olympiad
Document Type : Sample Question Paper
Category or Subject : Science
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International Junior Science Olympiad Paper

** International Junior Science Olympiad (IJSO) is a competition in science for students who are fifteen years or younger on 31 st December of the competition year.

Related : IJSO International Junior Science Olympiad MCQ Sample Question Paper 2017 : www.pdfquestion.in/23039.html

IJSO aims to promote interest in science among school students, exposing them to problem solving, critical thinking and experimentation. Over the years IJSO aims to positively impact science and mathematics education at school level.

IJSO Syllabus

** The syllabus of the International Junior Science Olympiad (IJSO) lists the skills and areas of knowledge the participants should be familiar with for this competition.

** It thus serves as a guideline for developing tasks to the Scientific Committees of the hosting countries but should also help the leaders of the participating countries to effectively train their students for this competition.

** In order to keep the syllabus up to date it should be revalidated every three years and if necessary shortened or expanded.

IJSO Theory Question Papers

I. Essential Oil of Clove and Virgin Coconut Oil (VCO)
Eugenol is a phenylpropene, an allyl chain-substituted guaiacol (Figure I.1a). Eugenol is a member of the phenylpropanoids class of chemical compounds. It is a colourless to pale yellow oily liquid (Figure I.Ib) extracted from certain essential oils especially from clove oil, nutmeg, cinnamon, basil and bay leaf.

It is present in concentrations of 80–90% in clove bud oil and 82–88 % in oil of clove leaf (Figure I.1c). Until modern times, cloves grew only on a few islands in the Maluku Islands (the Moluccas). Today, Indonesia, Madagascar, Zanzibar, Pakistan and Sri Lanka are world leader in clove output. Eugenol is used in perfumes, flavorings, and essential oils.

It is also used as a local antiseptic and anaesthetic. Eugenol can be combined with zinc oxide to form a material – known as zinc oxide eugenol (ZOE) – which has restorative and prosthodontic applications in dentistry. For example, zinc oxide eugenol is used for root canal sealing.

Questions :
I.1 [1.5 point] Eugenol (Fig. 1a) is a monoprotic weak acid with Ka = 6.5 x 10-11. If 1.64 g of eugenol (molar mass 164 g mol-1) is dissolved in water to final volume of 1.00 L, the pH of the solution is …..

I.2 [0.5 point] Eugenol extracted from clove (Syzygium aromaticum) contains the elements carbon, hydrogen and oxygen combined in a ratio of 6.0 g of hydrogen, 60.0 g of carbon and 16.0 g of oxygen. If a given sample of eugenol was found to contain 128.0 g of oxygen, calculate the content (in grams) of hydrogen and carbon in the sample.

I.3 [0.5 points] A closed reaction flask containing eugenol (C10H12O2) and ethyl bromide (C2H5Br) weighs 41.0 g. After reaction, an ether of eugenol (C12H16O2) and hydrogen bromide (HBr) were formed in the reaction flask according to the following reaction. 10H12O2 + C2H5Br ? C12H16O2 + HBr Determine the mass of the reaction flask with its contents after the reaction.

I.4 [1.0 point] Eugenol is considered as a weak acid with Ka = 6.5 x 10-11. If equal volumes of eugenol 0.02 M and 0.02 M HCl are mixed, calculate the pH of the mixture.

I.5 [1.5 point] A reaction of eugenol, C10H12O2 and diethylsulphate, (CH3CH2)2SO4 to form ether of eugenol follows 1:1 stoichiometric ratio. If 82.0 g of eugenol is mixed for reaction with 115.5 g of diethylsulphate, by the end of the reaction, how many grams of the unreacted reactant remain (Ar C=12, S=32, O=16, H=1).

Virgin coconut oil (VCO) is obtained from fresh and mature kernel (12 months old from pollination) of coconut (Cocos nucifera L.) by mechanical or natural means with or without the application of heat, which does not lead to alteration of the nature of the oil. VCO has not undergone chemical refining, bleaching or deodorizing. It can be consumed in its natural state without the need for further processing. VCO consists mainly of medium chain triglycerides which are resistant to peroxidation. The fatty acids in VCO are distinct from animal fats which contain mainly of long chain saturated fatty acids. VCO is colorless, free of sediment with natural fresh coconut scent. It is free from rancid odor or taste.

Questions :
I.6 [1.5 points] For the purpose of determination of the acid value of coconut oil sample, a 2.0 g of sample is mixed with 30.0 mL of 0.250 M KOH solution. After a complete reaction, the excess of KOH is back-titrated with 0.250 M HCl and requires 10.0 mL. If the acid value is defined as the mass of KOH in mg required to neutralize 1.0 g of substance, calculate the acid value of the sample. (atomic mass K = 39, O =16, H = 1).

I.7 [1.0 point] The major constituents of saturated fatty acid in VCO are lauric acid (C11H23COOH), myristic acid (C13H27COOH) and palmitic acid (C15H31COOH). If these fatty acids are separated by TLC (thin layer chromatography) using a plate coated with polar adsorbent and non-polar solvent, arrange in order (from low to high) of retardation factor (Rf) of these fatty acids

I.8 [1.5 point] The major component of fatty acids in VCO is lauric acid. 100 g of lauric acid (C11H23COOH) reacts with 160 mL of methanol (CH3OH) to form methyl laurate (C11H23COOCH3) according to the following reaction: C11H23COOH + CH3OH C11H23COOCH3 + H2O The equilibrium constant (Keq) of the reaction is 0.9 (H2O should be included in the equilibrium constant). Calculate the mass of methyl laurate formed (Atomic mass C=12, H=1, O=16; methanol density = 0.8 g/mL)

I.9 [1.0 points] Polyvinyl chloride (PVC) is one of the most used plastics for containers of various liquids including VCO. The raw material for the preparation of PVC, C2H3Cl is prepared based on the following reaction: C2H2 + HCl ? C2H3Cl. If 26.0 g of C2H2 is mixed with 40.0 g of HCl, calculate the weight (in grams) of C2H3Cl that will be formed after the reaction is complete. (Ar H = 1, C=12 and Cl = 35.5).