Candidate Number. In addition to this paper you will require: a calculator. Number

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1 Surname Other Names Leave blank Centre Number Candidate Number Candidate Signature General Certificate of Education January 2005 Advanced Subsidiary Examination CHEMISTRY CHM2 Unit 2 Foundation Physical and Inorganic Chemistry Tuesday 11 January 2005 Morning Session In addition to this paper you will require: a calculator. Number For Examiner s Use Mark Number Mark Time allowed: 1 hour Instructions Use blue or black ink or ball-point pen. Fill in the boxes at the top of this page. Answer all questions in Section A and Section B in the spaces provided. All working must be shown. Do all rough work in this book. Cross through any work you do not want marked. The Periodic Table/Data Sheet is provided on pages 3 and 4. Detach this perforated sheet at the start of the examination Information The maximum mark for this paper is 60. Mark allocations are shown in brackets. This paper carries 30 per cent of the total marks for AS. For Advanced Level this paper carries 15 per cent of the total marks. You are expected to use a calculator where appropriate. The following data may be required. Gas constant R = 8.31JK 1 mol 1 Your answers to the question in Section B should be written in continuous prose, where appropriate. You will be assessed on your ability to use an appropriate form and style of writing, to organise relevant information clearly and coherently, and to use specialist vocabulary, where appropriate. Advice You are advised to spend about 45 minutes on Section A and about 15 minutes on Section B. Total (Column 1) Total (Column 2) TOTAL Examiner s Initials CHM2

2 2 LEAVE MARGIN BLANK SECTION A Answer all questions in the spaces provided. 1 (a) State the trend in the boiling points of the halogens from fluorine to iodine and explain this trend. Trend... Explanation (4 marks) (b) Each of the following reactions may be used to identify bromide ions. For each reaction, state what you would observe and, where indicated, write an appropriate equation. (i) The reaction of aqueous bromide ions with chlorine gas Observation... Equation... (ii) The reaction of aqueous bromide ions with aqueous silver nitrate followed by the addition of concentrated aqueous ammonia Observation with aqueous silver nitrate... Equation... Observation with concentrated aqueous ammonia... (iii) The reaction of solid potassium bromide with concentrated sulphuric acid Observation 1... Observation 2... (7 marks) (c) Write an equation for the redox reaction that occurs when potassium bromide reacts with concentrated sulphuric acid.... (2 marks) 13

3 3 The Periodic Table of the Elements The atomic numbers and approximate relative atomic masses shown in the table are for use in the examination unless stated otherwise in an individual question. I II III IV V VI VII He Helium Key Ne Neon F Fluorine O Oxygen N Nitrogen C Carbon B Boron relative atomic mass Li Lithium 3 atomic number 9.0 Be Beryllium H Hydrogen Li Lithium Ar Argon Cl Chlorine S Sulphur P Phosphorus Si Silicon Al Aluminium Mg Magnesium Na Sodium Kr Krypton Br Bromine Se Selenium As Arsenic Ge Germanium Ga Gallium Zn Zinc Cu Copper Ni Nickel Co Cobalt Fe Iron Mn Manganese Cr Chromium V Vanadium Ti Titanium Sc Scandium Ca Calcium K Potassium Xe Xenon I Iodine Te Tellurium Sb Antimony Sn Tin In Indium Cd Cadmium Ag Silver Pd Palladium Rh Rhodium Ru Ruthenium Tc Technetium Mo Molybdenum Nb Niobium Zr Zirconium Y Yttrium Sr Strontium Rb Rubidium Rn Radon At Astatine Po Polonium Bi Bismuth Pb Lead Tl Thallium Hg Mercury Au Gold Pt Platinum Ir Iridium Os Osmium Re Rhenium W Tungsten Ta Tantalum Hf Hafnium La Lanthanum 57 * Ba Barium Cs Caesium Ac Actinium Ra Radium Fr Francium Lu Lutetium Yb Ytterbium Tm Thulium Er Erbium Ho Holmium Dy Dysprosium Tb Terbium Gd Gadolinium Eu Europium Sm Samarium Pm Promethium Nd Neodymium Pr Praseodymium Ce Cerium 58 * Lanthanides (260) Lr Lawrencium 103 (259) No Nobelium 102 (258) Md Mendelevium 101 (257) Fm Fermium 100 (252) Es Einsteinium Cf Californium Bk Berkelium Cm Curium Am Americium Pu Plutonium Np Neptunium U Uranium Pa Protactinium Th Thorium Actinides

4 4 Table 1 Proton n.m.r chemical shift data Type of proton δ/ppm RCH R 2 CH R 3 CH RCOCH ROCH RCOOCH ROH Table 2 Infra-red absorption data Bond Wavenumber/cm 1 C H C C C C C O C O O H (alcohols) O H (acids)

5 5 LEAVE MARGIN BLANK 2 (a) By referring to electrons, explain the meaning of the term oxidising agent.... (1 mark) (b) For the element X in the ionic compound MX, explain the meaning of the term oxidation state.... (1 mark) (c) Complete the table below by deducing the oxidation state of each of the stated elements in the given ion or compound. Oxidation state Carbon in CO 2 3 Phosphorus in PCl + 4 Nitrogen in Mg 3 N 2 (3 marks) (d) In acidified aqueous solution, nitrate ions, NO 3,react with copper metal forming nitrogen monoxide, NO, and copper(ii) ions. (i) Write a half-equation for the oxidation of copper to copper(ii) ions. (ii) Write a half-equation for the reduction, in an acidified solution, of nitrate ions to nitrogen monoxide. (iii) Write an overall equation for this reaction. (3 marks) 8 Turn over

6 6 LEAVE MARGIN BLANK 3 The curve below shows how the volume of oxygen evolved varies with time when 50 cm 3 of a 2.0 moldm 3 solution of hydrogen peroxide, H 2 O 2,decomposes at 298K. Volume of oxygen / cm 3 A Time / s (a) State how you could use the curve to find the rate of reaction at point A.... (1 mark) (b) Sketch curves, on the above axes, to illustrate how the volume of oxygen evolved would change with time if the experiment was repeated at 298K using the following. (i) 100 cm 3 of a 1.0 moldm 3 solution of H 2 O 2.Label this curve X. (ii) 25 cm 3 of a 2.0 moldm 3 solution of H 2 O 2 in the presence of a catalyst. Label this curve Y. (4 marks)

7 7 LEAVE MARGIN BLANK (c) Hydrogen peroxide decomposes more rapidly in the presence of aqueous hydrogen bromide. The decomposition proceeds as shown by the following equations. H 2 O 2 + HBr HBrO + H 2 O HBrO + H 2 O 2 H 2 O + O 2 + HBr (i) Write an equation for the overall reaction. (ii) Define the term catalyst. (iii) Give two reasons, other than an increase in the reaction rate, why these equations suggest that hydrogen bromide is behaving as a catalyst. Reason 1... Reason 2... (5 marks) 10 TURN OVER FOR THE NEXT QUESTION Turn over

8 8 LEAVE MARGIN BLANK 4 (a) When iron(iii) oxide is reduced in the Blast Furnace, both carbon and carbon monoxide act as reducing agents. (i) Write an equation to illustrate how carbon monoxide is formed in the Blast Furnace. (ii) Write an equation to illustrate how carbon monoxide reduces iron(iii) oxide. (iii) Suggest in terms of collisions why, in the Blast Furnace, carbon monoxide reacts more rapidly with iron(iii) oxide than does carbon. (4 marks) (b) State why carbon is not used to reduce the oxide of titanium to the metal.... (1 mark) (c) (i) Name the converter that is used to remove impurities from the iron obtained from a Blast Furnace. (ii) Write an equation to illustrate how the sulphur impurity is removed from the iron. (iii) State how the phosphorus impurity is removed from iron in this converter. (iv) Explain two major benefits of using some scrap iron in this converter. Benefit 1... Benefit 2... (7 marks) (d) Give two reasons why titanium is a more expensive metal than iron. Reason 1... Reason 2... (2 marks) 14

9 9 LEAVE MARGIN BLANK SECTION B Answer the question below in the space provided on pages 9 to 12 of this booklet. 5 Methanol, CH 3 OH, is a convenient liquid fuel. (a) An experiment was conducted to determine the enthalpy of combustion of liquid methanol. The energy obtained from burning 2.12g of methanol was used to heat 150g of water. The temperature of the water rose from 298 K to 362 K. (The specific heat capacity of water is 4.18 JK 1 g 1 ) (i) (ii) Define the term standard enthalpy of combustion. Use the data above to calculate a value for the enthalpy of combustion of one mole of liquid methanol. (7 marks) (b) Methanol can be synthesised from methane and steam by a process that occurs in two stages. Stage 1 CH 4 (g) + H 2 O(g) 3H 2 (g) + CO(g) H = +206kJmol 1 Stage 2 CO(g) + 2H 2 (g) CH 3 OH(g) H = 91kJmol 1 (i) (ii) Explain why, in Stage 1, a higher yield of hydrogen and carbon monoxide is not obtained if the pressure is increased. Stage 2 is carried out at a compromise temperature of 500K. By considering what would happen at higher and lower temperatures, explain why 500 K is considered to be a compromise for Stage 2. (5 marks) (c) The standard enthalpies of combustion of carbon monoxide and of hydrogen are 283 kj mol 1 and 286 kj mol 1, respectively. Use these data and the enthalpy change for Stage 2 to calculate a value for the standard enthalpy of combustion of gaseous methanol. (3 marks) END OF QUESTIONS Turn over

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12 12 LEAVE MARGIN BLANK Copyright 2005 AQA and its licensors. All rights reserved.

13 GCE 2005 January Series abc Mark Scheme Chemistry CHM2 Foundation Physical and Inorganic Chemistry Mark schemes are prepared by the Principal Examiner and considered, together with the relevant questions, by a panel of subject teachers. This mark scheme includes any amendments made at the standardisation meeting attended by all examiners and is the scheme which was used by them in this examination. The standardisation meeting ensures that the mark scheme covers the candidatesí responses to questions and that every examiner understands and applies it in the same correct way. As preparation for the standardisation meeting each examiner analyses a number of candidatesí scripts: alternative answers not already covered by the mark scheme are discussed at the meeting and legislated for. If, after this meeting, examiners encounter unusual answers which have not been discussed at the meeting they are required to refer these to the Principal Examiner. It must be stressed that a mark scheme is a working document, in many cases further developed and expanded on the basis of candidatesí reactions to a particular paper. Assumptions about future mark schemes on the basis of one yearís document should be avoided; whilst the guiding principles of assessment remain constant, details will change, depending on the content of a particular examination paper.

14 Further copies of this Mark Scheme are available to download from the AQA Website: Copyright 2005 AQA and its licensors. All rights reserved. COPYRIGHT AQA retains the copyright on all its publications. However, registered centres for AQA are permitted to copy material from this booklet for their own internal use, with the following important exception: AQA cannot give permission to centres to photocopy any material that is acknowledged to a third party even for internal use within the centre. Set and published by the Assessment and Qualifications Alliance. The Assessment and Qualifications Alliance (AQA) is a company limited by guarantee registered in England and Wales and a registered charity number Registered address AQA, Devas Street, Manchester. M15 6EX. Dr Michael Cresswell Director General

15 Mark Scheme Advanced Subsidiary / Advanced - Chemistry Guidance on the award of the mark for Quality of Written Communication Quality of Written Communication assessment requires candidates to: select and use a form and style of writing appropriate to purpose and complex subject matter; organise relevant information clearly and coherently, using specialist vocabulary when appropriate; and ensure text is legible, and spelling, grammar and punctuation are accurate, so that meaning is clear. For a candidate to be awarded 1 mark for quality of written communication on the question identified as assessing QWC in a unit test, the minimum acceptable standard of performance should be: the longer parts (worth 4 marks or more) should be structured in a reasonably logical way, appropriate and relevant to the question asked; ideas and concepts should be explained sufficiently clearly to be readily understood. Continuous prose should be used and sentences should be generally be complete and constructed grammatically. However, minor errors of punctuation or style should not disqualify; appropriate AS/A level terminology should be used. Candidates should not use such phrases as ëfighting diseaseí, ëmessages passing along nervesí, ëenzymes being killedí etc, but a single lapse would not necessarily disqualify. Technical terms should be spelled correctly, especially where confusion might occur, e.g. mitosis/meiosis, glycogen/glucagon. The Quality of Written Communication mark is intended as a recognition of competence in written English. Award of the mark should be based on overall impression of performance on the question identified on the paper as assessing QWC. Perfection is not required, and typical slips resulting from exam pressure such as ëofí for ëoffí should not be penalised. Good performance in one area may outweigh poorer performance in another. Care should be taken not to disqualify candidates whose lack of knowledge relating to certain parts of a question hampers their ability to write a clear and coherent answer; in such cases positive achievement on other questions might still be creditworthy. No allowance should be made in the award of this mark for candidates who appear to suffer from dyslexia or for whom English is a second language. Other procedures will be used by the Board for such candidates. Examiners should record 1 or 0 at the end of the paper in the Quality of Written Communication lozenge. This mark should then be transferred to the designated box on the cover of the script. 3

16 Chemistry ñ Advanced Subsidiary / Advanced Mark Scheme CHM2 Foundation Phyiscal and Inorganic Chemistry Section A Question 1 (a) Increase 1 Van der Waalís forces between molecules 1 Increase with size (or M r or surface area etc) 1 More energy needed to break (overcome) these forces 1 (Note max 2 from last three marks if no mention of molecules or ëmolecularí) (b) (i) Brown solution (or yellow or orange) 1 Cl 2 + 2Br ñ 2Cl ñ + Br 2 1 (ii) cream precipitate 1 Br ñ + Ag + AgBr 1 Precipitate dissolves 1 (iii) orange (brown) fumes (gas), White fumes (or misty fumes), choking gas (any 2) 2 (c) 2H + + H 2 SO 4 + 2Br ñ- SO 2 + Br 2 + 2H 2 O (SO 2 and Br 2 (1), equation (1)) 2 Question 2 Total 13 (a) Accepts electrons 1 (b) Charge on the ion (or element or atom) 1 (c) ñ3 1 (d) (i) Cu Cu e ñ 1 (ii) NO ñ 3 + 4H + +3e ñ NO +2H 2 O 1 (iii) 3Cu + 2NO ñ 3 +8H + 3Cu 2+ +2NO + 4H 2 O 1 Total 8 4

17 Mark Scheme Advanced Subsidiary / Advanced - Chemistry Question 3 (a) Gradient (or slope) (or draw a tangent) 1 (b) (i) Curve X is lower and starts at origin 1 And levels out at same volume as original curve 1 (ii) Curve Y is steeper than original and starts at origin 1 Then levels out at half the volume of the original 1 (c) (i) 2H 2 O 2 2H 2 O + O 2 1 (ii) Speeds up (alters the rate of) a chemical reaction 1 Remains unchanged (or not used up) 1 (iii) Remains unchanged (or not used up or not in the overall reaction equation) 1 Offers alternative reaction route (or acts as an intermediate) 1 Question 4 Total 10 (a) (i) C + CO 2 2CO (or 2C + O 2 2CO, or carbon reduction of an iron oxide) 1 (ii) 3CO + Fe 2 O 3 3CO 2 + 2Fe 1 (iii) CO is gaseous (or C is solid) 1 CO has more collisions (or C has very few collisions) 1 (b) Titanium carbide is stable. 1 (c) (i) Basic oxygen process (or BOS) 1 (ii) Mg + S MgS 1 (iii) React with oxygen 1 Forms phosphorus oxide (or P 4 O 10 ) 1 Removed as slag (or phosphate) (with CaO) 1 (iv) Any two from the following: saves energy, removes scrap from environment, uses fewer raw materials, fewer green house gases released, less CO released, less SO2 released, less mining, has greater % of iron, correct economic argument etc 2 (d) Cost of chlorine or sodium (or Mg) or argon or batch process (cost is QL mark) 1 Mention of another of these 1 Total 14 5

18 Chemistry ñ Advanced Subsidiary / Advanced Mark Scheme SECTION B Question 5 (a) (i) enthalpy change when 1 mol of a substance (or compound) (QL mark) 1 is (completely) burned in oxygen (or reacted in excess oxygen) 1 at 298 K and 100 kpa (or under standard conditions) 1 (ii) heat produced = mass of water Sp heat capacity T (or mc T) 1 = (note if mass = 2.12 lose first 2 marks then conseq) = J or = 40.1 kj (allow 39.9 ñ 40.2 must have correct units) 1 moles methanol = mass/m r = 2.12/32 (1) 1 = H = ñ 40.1/ = ñ 605 kj (mol ñ1 ) (allow ñ602 to ñ608 or answer in J) 1 (note allow conseq marking after all mistakes but note use of 2.12 g loses 2 marks Total 7 (b) (i) equilibrium shifts to left at high pressure 1 because position of equilibrium moves to favour fewer moles (of gas) 1 (ii) at high temperature reaction yield is low (or at low T yield is high) 1 at low temperature reaction is slow (or at high T reaction is fast) 1 therefore use a balance (or compromise) between rate and yield 1 Total 5 (c) H = Σ Hc o o (reactants) ñ Σ Hc (products) (or correct cycle) 1 Hc o (CH 3OH) = Hc o o (CO) + 2 Hc (H 1 2) ñ H = (ñ283) + (2 ñ286) ñ (ñ91) (mark for previous equation or this) = ñ764 (kj mol ñ1 ) ( units not essential but lose mark if units wrong) (note scores 1/3) Total 3 6