Edexcel Jun 2009 Paper 3 Q1 (with explained solutions) |

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Edexcel Jun 2009 Paper 3 Q1

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PMT Answer ALL the questions. Write your answers in the spaces provided. (a) A student carries out a series of tests on X, a white powder known to be either calcium carbonate or magnesium carbonate. Complete the table below. (6) Test Observation Inference (i) Carry out a flame test on X.Cation is magnesium.(ii) Add dilute hydrochloric acid to X.A gas is evolved.and a solution Y is formed. (iii) Pass the gas evolved in test (ii) through limewater.Gas evolved in (ii) is(iv) Add dilute sodium hydroxide to solution Y until there is no further change.The new substance observed is*N34473A0216*<br />
PMT (b) A student carries out a series of tests on a white solid Z which contains one cation and one anion. Complete the table below. (6) Test Observation Inference (i) Carry out a flame test on Z. Red flame Cation is eitheror(ii) Acidify an aqueous solution of Z with dilute nitric acid. Then add a few drops of aqueous silver nitrate followed by concentrated aqueous ammonia until there is no further change. (iii) Add concentrated sulfuric acid to solid Z. (iv) Test the gases formed in (iii) with a piece of filter paper soaked in potassium dichromate(VI) solution. Cream precipitate which Anion is probably bromide.Steamy fumes andvapour seen. Colour change fromtoProbably hydrogen bromide andformed. Bromide confirmed. Sulfur dioxide present. (v) Explain, in terms of the redox processes occurring, how sulfur dioxide is produced in (b)(iii). (2)(Total for Question 1 = 14 marks) *N34473A0316* Turn over<br />

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6CH07/01 Question Number 1 (a)(i) Correct Answer No (colour) change (to flame) OR no flame colour Accept No colour Reject White flame Correct Answer Reject Effervescence / bubbling / fizzing IGNORE hissing Reject Turns white Correct Answer Observation: (Lime water) turns milky / cloudy or white precipitate (formed) (1) Accept White solid (formed) / chalky Inference: carbon dioxide / CO2 (1) Correct Answer Reject Observation: White precipitate (formed) (1) Accept White solid / crystal (formed) IGNORE references to heat given out and to precipitate insoluble in excess Inference: Magnesium hydroxide / Mg(OH)2 (1) White substance Confirms magnesium present Correct Answer Reject Lithium / Li+ (1) Strontium / Sr2+ (1) Accept Calcium / Ca2+ (1) Rubidium Li, Sr, Ca (penalise use of element symbol once only) Correct Answer Reject Dissolves (in the ammonia) (to form a colourless solution) Accept Soluble IGNORE references to dilute ammonia Partially dissolves Question Number 1 (a)(ii) Question Number 1 (a)(iii) Question Number 1 (a)(iv) Question Number 1 (b)(i) Question Number 1 (b)(ii) Mark Mark Mark Mark Mark Mark<br />
Correct Answer Reject Observation: Brown or red-brown or orange (1) Inference: Bromine / Br2 (1) Red Bromide (for bromine) Correct Answer From: Orange or yellow To: blue or green or blue-green Correct Answer Reject Reject Mark two points independently (Hydrogen) bromide oxidized / bromine oxidation number increased (from 1 to 0) / changes from -1 to 0 /Bromide loses an electron / (hydrogen) bromide is a reducing agent (1) sulfuric acid reduced / sulfur oxidation number decreases (from (+)6 to (+)4) / changes from (+)6 to (+)4 / sulfate gains electrons / sulfuric acid is an oxidizing agent (1) Accept (+)VI to (+)IV sulfate reduced Correct Answer Reject Vertical line at 3.5 minutes intersects extrapolated top line (1) Horizontal extrapolated lower line and 66-69 minus 20-22 = (cid:1)T (1) incorrect or no extrapolation line joining points at 3 & 4 minutes & extrapolated to intersect top line (0) Correct Answer (1 x 50 x 103) = 0.0500 IGNORE sf Correct Answer Reject Reject 65.4 x 0.05 = 3.27 (g) / 3.3 (g) Accept 65 x 0.05 = 3.25 (g) / 3.3 (g) Mark Mark Mark Mark Mark Mark Question Number 1 (b)(iii) Question Number 1 (b)(iv) Question Number 1 (b)(v) Question Number 2 (a)(i) Question Number 2 (a)(ii) Question Number 2 (a)(iii)<br />

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