Skip to content
Edexcel Jun 2013 Paper 6 Q1
Answers available below
Show answer
Question
1
2
3
4
![Answer ALL the questions. Write your answers in the spaces provided. (a) Compound Z is a crystalline solid that contains a nickel cation and one type of anion. Complete the table below. Test Observation Inference (i) Add dilute sulfuric acid to compound Z Bubbles of a colourless gas are released. The gas turns limewater milky and acoloured solution is formed Yellow-brown solution forms Green precipitate forms(1) Name of gas released isFormula of anion in Z is(1) Formula of the complex ion formed is [Ni(H2O)6]2+(aq) Formula of the complex ion formed isFormula of the precipitate formed isFormula of the complex ion formed is [Ni(NH3)6]2+ (2) (1) (1) (ii) Add concentrated hydrochloric acid to the solution containing [Ni(H2O)6]2+ ions (iii) Add a few drops of dilute aqueous ammonia to the solution containing [Ni(H2O)6]2+ ions (iv) Add excess dilute aqueous ammonia to the solution containing [Ni(H2O)6]2+ ions until no further change is observed *P41653A0216*<br />
(b) A 10.0 cm3 sample of a solution containing [Ni(H2O)6]2+ ions was titrated with a solution of concentration 0.010 mol dm3 with respect to the ligand EDTA4 ions. The equation for the reaction is [Ni(H2O)6]2+ + EDTA4 o [Ni(EDTA)]2 + 6H2O (i) The mean titre of the solution containing EDTA4 ions was 24.20 cm3. Use this information, and the equation above, to calculate the concentration in mol dm3 of the solution containing [Ni(H2O)6]2+ ions. (ii) Assuming the total error in the measurement of the mean titre is 0.10 cm3, calculate the percentage error in this titre. (iii) A similar solution, containing the same concentration of [Ni(H2O)6]2+ ions, also contained a small amount of an impurity, copper(II) sulfate. Suggest what effect this impurity would have on the titre. Justify your answer. (2) (1) (2)(Total for Question 1 = 11 marks) *P41653A0316* Turn over<br />
BLANK PAGE *P41653A0416*<br />](https://learnah.org/wp-content/uploads/2018/08/l_smalljpgJune_2013_QP_-_Unit_6_Edexcel_Chemistry_A-level_1-0.jpg)
![Reject Blue-Green Turquoise Mark Mark Mark Mark Reject Reject Reject Blue-green Precipitate dissolves to give incorrect coloured solution Acceptable Answers Green IGNORE qualifications of green such as light / dark / emerald (1) Carbon dioxide ALLOW CO2 (1) CO3 ALLOW HCO3 Acceptable Answers(1) 2 Question Number 1(a)(i) Question Number 1(a)(ii) [NiCl4]2 ALLOW -2 for 2- NiCl4 [Ni(H2O)2Cl4]2- [NiCl6]4- Acceptable Answers 2- [Ni(Cl)4]2- Ni(Cl)4 2- Question Number 1(a)(iii) Ni(OH)2 / Ni(H2O)4(OH)2 / Ni(OH)2 (H2O)4 / [Ni(H2O)4(OH)2] / [Ni(OH)2 (H2O)4] Acceptable Answers Question Number 1(a)(iv) Blue solution (forms) ALLOW lavender blue solution and any other shade of blue OR (Green) precipitate dissolves<br />
Reject Mark Reject 4 or more SF Reject Mark Mark Acceptable Answers 24.2 / 1000 x 0.01 = 2.42 x 104 (mol) (1) Concentration of [Ni(H2O)6]2+ ions = 2.42 x 104 x 100 = 0.0242 (mol dm3) (1) ALLOW TE on number of moles Correct answer alone scores both marks IGNORE significant figures except 1 Acceptable Answers 0.1 / 24.2 x 100 = () 0.413% / () 0.41 % / () 0.4% Acceptable Answers (Mean) titre would be greater (1) EDTA(4) would also complex to / react with Cu2+ / [Cu(H2O)6]2+ / CuSO4 / copper ions / copper sulphate (1) Both marks are stand alone. More needed to react with unspecified impurity Total for Question 1 = 11 Marks Question Number 1(b)(i) Question Number 1(b)(ii) Question Number 1(b)(iii)<br />
Acceptable Answers Reject White smoke Reject Just OH group Hydroxide group Reject Either aldehyde or ketone on its own Reject Reject Mark Mark Mark Mark Mark (hydrogen atoms / protons on) benzene ring / phenyl group / arene ring Hydrogen atoms in phenol Smoky / sooty flame IGNORE reference to yellow flame Acceptable Answers It contains a phenol group / has OH attached to benzene ring ALLOW hydroxyl group attached to benzene ring ALLOW is a phenol ALLOW drawn benzene ring with OH Acceptable Answers It could be an aldehyde or a ketone / contains a carbonyl group ALLOW C=O Acceptable Answers ALLOW aromatic ketone ALLOW R-CO-R ALLOW not an aldehyde if both ketone and aldehyde mentioned in b(ii) Acceptable Answers Question Number 2(b)(iii) X is a ketone Question Number 2(a) Question Number 2(b)(i) Question Number 2(b)(ii) Question Number 2(c)(i)<br />](https://learnah.org/wp-content/uploads/2018/08/June_2013_MS_-_Unit_6_Edexcel_Chemistry_A-level_1-0.jpg)
