January 2008 edexcel AS chemistry unit 2 paper

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Surname Initial(s)
Centre
Paper Reference
No.
Signature
Candidate
No. 6 2 4 1 0 1
Paper Reference(s)
6241/01 Examiner's use only
Edexcel GCE Team Leader's use only
Chemistry
Advanced Subsidiary Question Leave
Number Blank
Unit Test 1 1
Thursday 17 January 2008 ­ Morning 2
Time: 1 hour 3
4
5
Materials required for examination Items included with question papers 6
Nil Nil
Candidates may use a calculator.
Instructions to Candidates
In the boxes above, write your centre number, candidate number, your surname, initial(s) and
signature.
Answer ALL the questions. Write your answers in the spaces provided in this question paper.
Show all the steps in any calculations and state the units.
Information for Candidates
The total mark for this paper is 60. The marks for individual questions and parts of questions are
shown in round brackets: e.g. (2). There are 16 pages in this question paper. All blank pages are
indicated.
A Periodic Table is printed on the back cover of this question paper.
Advice to Candidates
You are reminded of the importance of clear English and careful presentation in your answers.
Total
This publication may be reproduced only in accordance with
Edexcel Limited copyright policy.
©2008 Edexcel Limited. Turn over
Printer's Log. No.
N29259A
W850/R6241/57570 7/7/7/3/3/12,700
*N29259A0116*

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Page 2

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Answer ALL questions. Write your answers in the spaces provided.
1. (a) Complete the electronic configuration of a copper atom and a bromide ion.
(i) Copper atom, Cu 1s22s22p63s23p6 ...................................................................
(1)
(ii) Bromide ion, Br­ 1s22s22p63s23p6 ...................................................................
(1)
(b) Define the term relative atomic mass.
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(2)
(c) The following data were obtained for a mass spectrum of a sample of copper.
Relative isotopic mass Percentage abundance
62.93 69.17
64.93 30.…read more

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(d) Copper occurs naturally as the mineral malachite. The composition, by mass, of
malachite is as follows:
Cu = 57.5% C = 5.4% O = 36.2% H = 0.9%
(i) Calculate its empirical formula.
(2)
(ii) The molar mass of malachite is 221 g mol­1. Calculate its formula.
(1)
(e) Copper forms a chloride, CuCl2. Use the data below to calculate the maximum and
the minimum values for the molar mass of CuCl2.…read more

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2. (a) Lithium chloride, potassium carbonate and sodium iodide can be distinguished using
flame tests. Complete the table below.
Formula Flame colour
lithium chloride LiCl
potassium carbonate K2CO3
sodium iodide NaI
(2)
(b) Explain the origin of the colours in the flame test.
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(2)
(c) Write equations for the following reactions. Do not include state symbols.
(i) Lithium chloride and concentrated sulphuric acid.
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(1)
(ii) Potassium carbonate and dilute nitric acid.
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(d) Beryllium chloride, BeCl2, is covalent.
(i) Use ideas of ion polarisation or electronegativity to suggest why beryllium
chloride, a compound of a metal and a non-metal, is covalent rather than ionic.
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(2)
(ii) Draw a `dot and cross' diagram to show the bonding in a beryllium chloride
molecule, BeCl2. In your diagram show all the outer shell electrons in the atoms
of beryllium and chlorine.…read more

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3. In hydrogen fluoride, HF, and water, H2O, the major intermolecular force is the hydrogen
bond.
(a) Draw a diagram to show the formation of hydrogen bonds between water molecules
in ice. Show at least three water molecules in your diagram and any relevant polarity
in the molecules.
(3)
(b) Suggest why water has a higher boiling temperature than hydrogen fluoride.
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(c) When hydrogen fluoride reacts with water it forms hydrogen ions. A lone pair of
electrons on the water molecule joins with the hydrogen ion, H+, to produce the ion
H3O+.
(i) Draw a diagram to show clearly the shape of the H3O+ ion.
(1)
(ii) Suggest an approximate value for the bond angle H--O--H in H3O+.
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(1)
(iii) The oxygen atom in water has two lone pairs of electrons.…read more

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4. (a) Explain the term reducing agent in terms of oxidation number change.
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(1)
(b) Write ionic half-equations (do not include state symbols) to show:
(i) chlorate(I) ions, ClO­, in acidic solution, being reduced to chlorine molecules
and water.
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(1)
(ii) chloride ions being oxidised to chlorine molecules.
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(1)
(c) Combine the two equations in (b) to show the effect of adding an acid to a mixture of
chlorate(I) ions and chloride ions.
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(e) Potassium chlorate, KClO3, decomposes on heating to give potassium chloride, KCl,
and oxygen, O2.
(i) Write the equation for this reaction. State symbols are not required.
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(1)
(ii) Show, by the use of oxidation numbers, why this is a redox reaction.
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5. (a) Cooking fuels and petrol for car engines need to be gases or liquids which vaporise
easily. This will be the case if the intermolecular forces are weak.
Two common fuels are methane, CH4, and 2,2,4-trimethylpentane, C8H18.
Electronegativity
carbon 2.1
hydrogen 2.5
(i) Explain the meaning of the term electronegativity.
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(2)
(ii) The C--H bond in methane has some polarity but overall the molecule is
non-polar.
Explain why methane is a non-polar molecule.
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