ALS1Q - Section 1/ Atoms, Molecules and Stoichiometry / 1...

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Section 1/ Atoms, Molecules and Stoichiometry / SKH Bishop Baker Secondary School AL Chemistry Section 1 Atoms, Molecules and Stoichiometry 80 IA Q.4 (d) Complete and balance the following equation by adding one reactant and one product, and necessary coefficients. IO 3 - (aq) + I - (aq) + I 3 - (aq) + (2 marks) 80 IB Q.5 (b) (i) Above is a schematic diagram of a mass spectrometer. What is the function of the components in compartment A ? (1 mark) (ii) The following mass spectrometer trace was obtained for a naturally occurring sample of an element X . (I) Give an interpretation of this trace. (1 mark) (II) Calculate the relative atomic mass of the naturally occurring sample to four significant figures. (1 mark) (iii) Using mass spectroscopy, an organic compound Y containing C, H and O, was found to have a relative molecular mass of 46.043. Given the following relative isotopic masses : C = 12.000, H = 1.008, O = 15.995 work out the possible formulae for Y . (2 marks) 81 IA Q.1 (a) 1
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Section 1/ Atoms, Molecules and Stoichiometry / The above apparatus was used to determine the relative molecular mass of propanone (acetone), by measuring volumes of known mass of propanone. The propanone was introduced into the gas syringe by means of a hypodermic syringe (not shown). (i) Where exactly should the propanone be introduced ? (1 mark) (ii) How could the amount of propanone introduced be determined ? (1 mark) (iii) Suggest two precautions that should be taken in order to achieve the best result. (2 marks) 81 IB Q.9 (a) The apparatus below was set up to follow the change in electrical conductivity during the titration of silver nitrate with potassium chloride. The following results were obtained : Volume of 0.10 M silver nitrate added / cm 3 0.00 4.00 8.00 12.00 16.00 20.00 Ammeter reading (arbitrary units conductivity) 2.5 2.3 2.1 2.4 3.2 4.0 (i) Using the given data, draw a graph of ammeter reading against volume of silver nitrate solution added. (2 marks) (ii) Referring to your graph, explain why there is a change of electrical conductivity during the course of the titration. (1 mark) (iii) In view of your explanation in (ii), comment on the overall shape of your graph. 2
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Section 1/ Atoms, Molecules and Stoichiometry / (3 marks) (iv) Determine the equivalence point from your graph and calculate the molar concentration of the potassium chloride solution. (3 marks) 82 IA Q.2 (a) Show how you would convert the molar gas constant from R = 82.05 cm 3 atm K - 1 mol - 1 to R = 8.314 J K - 1 mol - 1 . Given : 1 atm. = 101 325 N m - 2 (1 mark) 82 IIB Q.8 (a) An ore we found to contain 70% copper, 25% sulphur and 5% of a number of other elements. (i) Determine the approximate empirical formula of this ore (based on Cu and S only). Hence, suggest possible chemical compounds present in this ore.
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ALS1Q - Section 1/ Atoms, Molecules and Stoichiometry / 1...

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