Mock 2009 Flashcards
In an experiment to determine the mass of iron in an iron tablet, describe in detail the procedure for making up the 250 cm³ solution from the tablets.
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In an experiment to determine the mass of iron in an iron tablet, explain the colour change observed as the first few drops of the potassium manganate (VII), KMnO4 solution was added to the flask.
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In an experiment to determine the mass of iron in an iron tablet, how was the end-point detected?
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In an experiment to determine the mass of iron in an iron tablet, why was dilute sulfuric acid added before the titrations were commenced?
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In an experiment to determine the mass of iron in an iron tablet, explain why nitric acid could not be used to provide acidic conditions for this reaction.
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The titration reaction is described by the equation:
MnO₄- + 5Fe₂+ + 8H+ → Mn₂+ + 5Fe₃+ + 4H₂O
Calculate: (i) The concentration of the iron (II) solution in moles per litre.
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The titration reaction is described by the equation:
MnO₄- + 5Fe₂+ + 8H+ → Mn₂+ + 5Fe₃+ + 4H₂O
Calculate: (ii) The mass of iron (II) in one tablet.
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The titration reaction is described by the equation:
MnO₄- + 5Fe₂+ + 8H+ → Mn₂+ + 5Fe₃+ + 4H₂O
Calculate: (iii) The percentage by mass of iron (II) in each tablet.
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A group of students prepared ethanal (CH₃CHO) by slowly adding an aqueous solution of ethanol (C₂H₅OH) and sodium dichromate (VI) (Na₂Cr₂O₇.2H₂O) to a hot aqueous solution of sulfuric acid (H₂SO₄). State and explain two features of the preparation that are necessary to ensure the yield of ethanal is maximized.
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A group of students prepared ethanal (CH₃CHO) by slowly adding an aqueous solution of ethanol (C₂H₅OH) and sodium dichromate (VI) (Na₂Cr₂O₇.2H₂O) to a hot aqueous solution of sulfuric acid (H₂SO₄).The ethanol/oxidizing agent mixture was added slowly to the hot acid, explain why this was necessary.
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A group of students prepared ethanal (CH₃CHO) by slowly adding an aqueous solution of ethanol (C₂H₅OH) and sodium dichromate (VI) (Na₂Cr₂O₇.2H₂O) to a hot aqueous solution of sulfuric acid (H₂SO₄). State and explain the colour change which is observed during the addition of the ethanol and sodium dichromate (VI) solution to the hot acid.
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Describe how you would carry out the ‘Silver Mirror’ test on a sample of ethanal.
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If the students used 4.47g of sodium dichromate (VI) (Na₂Cr₂O₇.2H₂O) and they collected 2.0cm³ of ethanal (density 0.78g/cm³), in this experiment what was their % yield. [Relative atomic masses: H = 1, C = 12, O = 16, Na = 23, Cr = 52,]
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question 3 not in here
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Describe how a flame test may be carried out to determine the presence of a metal in a salt.
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In such a flame test, state the flame colour which indicates the presence of (i) the copper cation and (ii) the potassium cation in solution?
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Name the series of coloured lines in the line emission spectrum of hydrogen corresponding to transitions of electrons from higher energy levels to the second
(n = 2) energy level.
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Define electronegativity.
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What is the percentage by mass of chromium in sodium dichromate (VI) Na₂Cr₂O₇?
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Name the two reference hydrocarbons used to measure the octane number of a fuel.
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What are the two possible shapes of molecules of general formula AB₃?
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Name the product formed when bromine Br₂ is added to ethene C₂H₄.
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What is the oxidation number of manganese in (i) MnO and (ii) KMnO₄?
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Explain how particle size can affect the rate of a chemical reaction.
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What is the underlying principle of ultraviolet absorption spectroscopy (UV)?
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Give the systematic name of the two isomers of C₃H₆O.
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State two ways in which nitrogen fixation occurs in nature.
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Name the material used in the anode to extract sodium from its ore in a Downs Cell.
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Define first ionization energy.
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Account for the trend in first ionisation energies of the elements going down Group II of periodic table, i.e. the alkaline-earth metals.
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Define (i) energy level and (ii) atomic orbital.
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Write the electron configuration (s, p, etc.) of a chromium atom in its ground state.
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Use the electronegativity values provided in the log tables to predict the bond type in the following compounds. (i) NaBr, (ii) H₂O, (iii) PH₃
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State the shape of the H₂O molecule and explain it’s high boiling point.
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