A.M. WEDNESDAY, 26 May minutes

Transcription

1 Candidate Name Centre Number 0 Candidate Number GCSE 25/02 SCIENCE CEMISTRY IGER TIER CEMISTRY 3 A.M. WEDNESDAY, 26 May minutes For s use Question Maximum Mark Mark Awarded ADDITIONAL MATERIALS In addition to this paper you may require a calculator and a ruler. Total 50 INSTRUCTIONS TO CANDIDATES Write your name, centre number and candidate number in the spaces at the top of this page. Answer all questions. Write your answers in the spaces provided in this booklet. INFORMATION FOR CANDIDATES The number of marks is given in brackets at the end of each question or part-question. You are reminded of the necessity for good English and orderly presentation in your answers. The Periodic Table is printed on the back cover of the examination paper and the formulae for some common ions on the inside of the back cover. VP*(S )

2 Answer all questions. 1. (a) The equation below represents the preparation of ethanol from glucose solution, in the presence of yeast. C 6 12 O 6 2C 2 5 O + 2CO 2 (i) Write the word equation to represent the reaction above. [2] (ii) 2 Give the term for the process taking place when ethanol is formed from glucose solution. [1]... (b) Once the reaction stops, the unreacted yeast can be removed by filtering to recover a mixture of unreacted glucose solution and ethanol. The diagram below shows the apparatus which could then be used to separate ethanol from the unreacted glucose solution. thermometer flask water out A unreacted glucose solution and ethanol mixture cold water in (i) Give the reason why the ethanol can be separated from the unreacted glucose solution by this method. [1]... (25-02)

3 (ii) Give the name of 3 I. the process being used to obtain ethanol from the mixture, [1]... II. the change of state occurring in the flask, [1]... III. the change of state occurring in apparatus A. [1] (25-02) Turn over. 7

4 2. The temperature ranges for which enzyme activity occurs can be different for different enzymes. The graph below shows the amount of activity of an enzyme, A, over a temperature range. Amount of enzyme activity A Temperature / C (i) Use the graph to give the temperature when the amount of enzyme activity is greatest for enzyme A. [1]... C (ii) Sketch carefully the graph of the enzyme activity of a different enzyme, B, which is active between 0 and 55 C and has its greatest activity at 30 C. [2] (iii) Give a temperature value at which both enzymes would be inactive. [1]... C (25-02)

5 5 3. The diagram below shows the apparatus used to investigate the different dyes in five felt tipped pens, A, B, C, D and E. water strip of filter paper pen colour on reference line The following chromatograms were obtained from the five different coloured pens. separated dyes A B C D E (i) Give the letter of the pen which contains I. both the dyes found in pen D,... [1] II. the dyes found in both pens B and C.... [1] (ii) Pencils made from graphite are usually used to draw the reference line on the strips of filter paper used in chromatography experiments. Give the property of graphite that makes a pencil a more suitable choice than ink, for drawing reference lines. [1]... (iii) Describe how you would find the original colour of pen A from its chromatogram. [1]... (25-02) Turn over.

6 6. (a) The flow diagram below shows the reactions that occur to prepare slaked lime, Ca(O) 2, from limestone, CaCO 3. Reaction 1 CaCO 3 CaO + gas B Ca(O) 2 Process A Reaction 2 Add a few drops of liquid C (i) I. Give the term for the breakdown of calcium carbonate in Reaction 1. [1]... II. State what needs to be done to limestone for this to happen. [1]... (ii) Give the name of I. gas B,... [1] II. liquid C.... [1] (iii) Write a balanced symbol equation for Reaction 2. [3] (b) Name the metallic element which uses limestone during its extraction. [1]... (c) Give two disadvantages associated with limestone quarrying. [2] (25-02) 10

7 BLANK PAGE (25-02) Turn over.

8 5. (a) The molecular formulae of five carbon compounds are shown below. (i) (ii) C 3 6 C 10 C 3 8 C 2 5 O C 3 O A B C D E Give the letters of two carbon compounds which belong to the alkane homologous series. [1]... and... 8 Give the letter of the carbon compound which has the structural formula C C C Letter... [1] (b) Butane, C 10, has two chain isomers. (i) Draw the structures of both chain isomers of butane. [2] (ii) Use your structures to explain the meaning of the term isomer. [1] (25-02)

9 (c) X The flow diagram below shows two reactions of ethene. Br 2 C 9 C ethene gas G C C (i) Give the chemical name for I. gas G,... [1] II. the product of the reaction between ethene and gas G.... [1] (ii) Draw the structural formula for compound X, formed when ethene reacts with bromine. [1] (25-02) Turn over. 8

10 6. The main stages in the manufacture of sulphuric acid are given below. Stage 1: Stage 2: Stage 3: 10 Sulphur reacts with oxygen. Sulphur dioxide reacts with oxygen. Sulphur trioxide is absorbed into concentrated sulphuric acid and diluted to various concentrations. (i) Give the name of the raw material that is used in both stages 1 and 2. [1]... (ii) During Stage 2, gases are passed through a vanadium(v) oxide catalyst. The catalyst will not work below 00 C and breaks down above 620 C. The table below shows the % yield of sulphur trioxide at different temperatures in Stage 2. Temperature / C % Yield of sulphur trioxide (25-02)

11 11 Plot a graph of the % yield of sulphur trioxide at different temperatures, on the grid below. [3] % Yield of sulphur trioxide Temperature / C (iii) Use the graph to I. state how changing the temperature affects the % yield of sulphur trioxide, [1]... II. give the temperature range to be used to obtain a yield of sulphur trioxide above 90%. [1]... to... C (iv) Write a balanced symbol equation for the reaction between sulphur dioxide and oxygen, O 2, in Stage 2. [3] (25-02) Turn over. 9

12 12 7. The diagram below shows the apparatus used to find the concentration of a sample of dilute ethanoic acid. apparatus A dilute ethanoic acid 20.0cm 3 sodium hydroxide solution and 3 drops of indicator The acid was added a little at a time, using apparatus A. The volume of acid needed to change the indicator colour was recorded. The titration was repeated a number of times and an average volume of acid calculated. (i) Name the piece of apparatus labelled A in the diagram.... [1] (ii) State the purpose of the indicator. [1] (iii) Ethanoic acid reacts with sodium hydroxide solution according to the equation below. C 3 COO + NaO C 3 COONa + 2 O It was found that 25.0 cm 3 of dilute ethanoic acid was needed to neutralise 20.0 cm 3 of sodium hydroxide solution of concentration 0.25moldm 3. Calculate the concentration of the acid in moldm 3. [3] Concentration =... moldm 3 5 (25-02)

13 13 8. The flow charts below show tests carried out by Duncan on compounds A, B and C and the results of those tests. The compounds were known to include some of the following ions. ammonium calcium potassium sodium bromide carbonate iodide sulphate white precipitate formed Add dilute hydrochloric acid followed by barium chloride solution. Compound A Flame test yellow coloured flame cream precipitate formed Add dilute nitric acid followed by silver nitrate solution. Compound B Flame test lilac coloured flame gas given off, turns limewater milky Add dilute hydrochloric acid. Bubble gas given off into limewater. Compound C Add sodium hydroxide solution and warm the mixture. Test the gas given off with damp litmus. pungent smelling gas given off, turns damp litmus paper blue Use the information above to identify compounds A, B and C. [3] Compound A is... Compound B is... Compound C is... (25-02) Turn over. 3

14 1 BLANK PAGE (25-02)

15 Name POSITIVE IONS FORMULAE FOR SOME COMMON IONS Formula 15 Name NEGATIVE IONS Formula Aluminium Al 3+ Bromide Br Ammonium N + Barium Ba 2+ Calcium Ca 2+ Copper(II) Cu 2+ ydrogen + Iron(II) Fe 2+ Iron(III) Fe 3+ Lithium Li + Magnesium Mg 2+ Nickel Ni 2+ Potassium K + Silver Ag + Sodium Na + Carbonate CO 2 Chloride Cl Fluoride F ydroxide O Iodide I Nitrate NO Oxide O 2 Sulphate SO (25-02) Turn over.

16 elium Neon Fluorine Chlorine Bromine Selenium Boron Aluminium Gallium Zinc Copper Nickel Cobalt Iron Manganese Chromium Vanadium Titanium Scandium Calcium Potassium Magnesium Sodium Beryllium Lithium Arsenic Phosphorus Nitrogen Carbon Silicon Germanium Sulphur Oxygen Argon Krypton 2 Ne F 19 9 O 16 8 C 12 6 N 1 7 B 11 5 Ar 0 18 S P Si 28 1 Al Kr 8 36 Br Se 79 3 As Ge Ga Zn Cu 6 29 Ni Fe Co Mn V Cr 52 2 Ti 8 22 Sc 5 21 Ca 0 20 K Iodine Tellurium Indium Cadmium Silver Palladium Rhodium Ruthenium Molybdenum Niobium Zirconium Yttrium Strontium Rubidium Antimony Tin Xenon Xe I Te Sb Sn In Cd Ag Pd Ru 101 Rh Tc 99 3 Nb 93 1 Mo 96 2 Zr 91 0 Y Sr Rb Astatine Polonium Thallium Mercury Gold Platinum Iridium Osmium Rhenium Tungsten Tantalum afnium Lanthanum Barium Caesium Bismuth Lead Radon Rn At Po Bi Pb Tl g Au Pt Os Ir Re Ta W 18 7 f La Ba Cs Actinium Radium Francium Ac Ra Fr Mg 2 12 Na Be 9 Li 7 3 ydrogen Group PERIODIC TABLE OF ELEMENTS e Cl Z X A Name Element Symbol Atomic number Mass number Key: Technetium (25-02) 16