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Chemistry exam questions > Mock 2010 > Flashcards

Mock 2010 Flashcards

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1
Q

In an experiment to determine the total hardness of a water sample containing both calcium and magnesium ions, name the indicator used in this titration and state the colour change observed at the end point of the titration.

A

v

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2
Q

In an experiment to determine the total hardness of a water sample containing both calcium and magnesium ions, describe the correct procedure for rinsing the pipette and transferring the solution to the conical fl ask.

A

x

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3
Q

In an experiment to determine the total hardness of a water sample containing both calcium and magnesium ions, a small quantity of another solution is added before the titration proceeds. What is this solution and what is its purpose?

A

x

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4
Q

In an experiment to determine the total hardness of a water sample containing both calcium and magnesium ions, during the titration some of the solution in the conical flask got splashed high up the side of the conical flask. What should you do to rectify this situation? Why does this not affect the result of the experiment?

A

x

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5
Q

In an experiment to determine the total hardness of a water sample containing both calcium and magnesium ions, it was found that 100cm³ portions of the water sample required an average titre of 9.2 cm³ of 0.010 M edta solution. Calculate the total hardness in the sample in moles per litre.

A

x

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6
Q

In an experiment to determine the total hardness of a water sample containing both calcium and magnesium ions, it was found that 100cm³ portions of the water sample required an average titre of 9.2 cm³ of 0.010 M edta solution. Calculate the total hardness in the sample in grams per litre expressed in terms of CaCO₃.

A

x

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7
Q

In an experiment to determine the total hardness of a water sample containing both calcium and magnesium ions, it was found that 100 cm³ portions of the water sample required an average titre of 9.2 cm³ of 0.010 M edta solution. Calculate the total hardness in the sample in p.p.m. expressed in terms of CaCO₃.

A

x

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8
Q

In an experiment to determine the total hardness of a water sample containing both calcium and magnesium ions, if the water sample had been boiled would the titre value be bigger, smaller or remain the same? Explain your answer.

A

x

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9
Q

Ethanoic acid (CH₃COOH) is prepared using ethanol (C₂H₅OH) and acidified sodium dichromate (Na₂Cr₂O₇.2H₂O). What other substance should be placed in the flask? Explain why?

A

x

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10
Q

Ethanoic acid (CH₃COOH) is prepared using ethanol (C₂H₅OH) and acidified sodium dichromate (Na₂Cr₂O₇.2H₂O). State two features of the preparation that are necessary to maximise the yield of ethanoic acid and explain the reason for each.

A

x

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11
Q

Ethanoic acid (CH₃COOH) is prepared using ethanol (C₂H₅OH) and acidified sodium dichromate (Na₂Cr₂O₇.2H₂O). Describe and account for the colour change which is observed during the preparation.

A

x

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12
Q

Ethanoic acid (CH₃COOH) is prepared using ethanol (C₂H₅OH) and acidified sodium dichromate (Na₂Cr₂O₇.2H₂O). Describe how the ethanoic acid may be isolated from the mixture in the flask.

A

x

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13
Q

Ethanoic acid (CH₃COOH) is prepared using ethanol (C₂H₅OH) and acidified sodium dichromate (Na₂Cr₂O₇.2H₂O). Name two impurities which might be present alongside the ethanoic acid.

A

x

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14
Q

Ethanoic acid (CH₃COOH) is prepared using ethanol (C₂H₅OH) and acidified sodium dichromate (Na₂Cr₂O₇.2H₂O). Show clearly that ethanol was the limiting reagent when 13.8cm³ of ethanol (density 0.80g cm-³) was added to 59.6g of sodium dichromate, Na₂Cr₂O₇.2H₂O. Calculate the theoretical yield of ethanoic acid (CH₃COOH) in grams.

A

x

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15
Q

In the investigation to find the effect of temperature on a reaction rate, identify the pale yellow precipitate formed in the flask.

A

x

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16
Q

In the investigation to find the effect of temperature on a reaction rate, explain why increasing temperature has a significant effect on the rate of reaction.

A

x

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17
Q

State and explain three factors other than temperature that have an effect on the rate of a chemical reaction.

A

x

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18
Q

Write the electronic configuration (s.p.etc) of a chromium atom in its ground state.

A

x

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19
Q

What is the oxidation number of sulphur in (i) H₂SO₄ and (ii) Na₂S₂O₃?

A

x

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20
Q

Distinguish between sigma (ơ) and pi (π) covalent bonding.

A

x

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21
Q

How many atoms are present in 560 cm³ of methane at s.t.p.?

A

x

22
Q

Draw an energy profile diagram of an endothermic reaction and indicate on the diagram the activation energy.

A

x

23
Q

How could you test for the presence of nitrate ions in aqueous solution?

A

x

24
Q

What colour change will occur if concentrated sulfuric acid is added to the following equilibrium mixture? Give a reason for your answer.
2CrO₄ ²- + 2H⁺ ⇌ Cr₂0₇ ²- +H₂O

A

x

25
Q

Draw the structure and give the IUPAC name for CH₃COCH₃.

A

x

26
Q

Name two additives or two types of additives used to increase the octane number of a fuel.

A

x

27
Q

How is oxygen gas produced industrially?

A

x

28
Q

How does the anodising of aluminium protect it from corrosion?

A

x

29
Q

Define electronegativity.

A

x

30
Q

Explain why there is a general increase in electronegativity values across the periods in the periodic table of the elements.

A

x

31
Q

Explain, in terms of the structures of the atoms, the trend in reactivity down Group I (the alkali metal group) of the periodic table.

A

x

32
Q

Use the electronegativity values provided in the log tables to predict the bond type in the following compounds. (i) KCl , (ii) NH₃, (iii) H₂S

A

x

33
Q

Name the scientist who is credited with the discovery of radioactivity.

A

xx

34
Q

Define radioactivity.

A

x

35
Q

What is an alpha (α) particle and state two of its properties?

A

x

36
Q

Complete the equation for the nuclear reaction involved in the alpha decay of americium-241(Am) to neptunium (Np). (241, 95) Am → Np +

A

x

37
Q

Propane and butane are major components of LPG. What do the letters LPG stand for?

A

x

38
Q

Draw two structural isomers of butane.

A

x

39
Q

Why are mercaptans often added to LPG?

A

x

40
Q

Give one advantage and one disadvantage of using hydrogen as a fuel.

A

x

41
Q

What structural feature of 2,2,4-trimethylpentane results in it having a high octane rating and give one other structural feature which increases the octane number of a hydrocarbon.

A

x

42
Q

Define the heat of combustion of a compound.

A

x

43
Q

The combustion of butane is described by the following balanced equation. C4H10(g) + 6½O2(g) 4CO2(g) + 5H2O(l) Calculate the heat of combustion of butane given that the heats of formation of butane, carbon dioxide and water are –125, –394 and –286 kJ mol−1, respectively.

A

x **

44
Q

State Le Chatelier’s principle.

A

x

45
Q

What is meant by chemical equilibrium? Why is it described as a dynamic state?

A

x

46
Q

question 7 not in

A

x

47
Q

Other than heating, mention one way of reversing the change caused by cooling the reaction mixture. (equilibrium)

A

x

48
Q

Define (i) an acid, (ii) a base according to the Brønsted-Lowry theory.

A

x

49
Q

Identify the acid, and conjugate acid in the following system.
H₂SO₄ + HF ⇌ H₂F⁺ + HSO₄-

A

x

50
Q

Define pH.

A

x

51
Q

Describe clearly the processes involved in the primary and secondary stages of urban sewage treatment. What substances are removed by tertiary treatment of sewage?

A

x

52
Q

question 8 b

A

xx

Chemistry exam questions (29 decks)

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