11.3. Some reactions of the halide ions
A subsection of Chemistry, 9701, through 11. Group 17
Listing 10 of 171 questions
Complete the electronic configuration of the copper(ion. 1s22s22p6 State the colour of the solutions containing the following ions. ● [Cu(H2O)6]2+● [CuCl 4]2– Octahedral complexes of Cu2+ with different ligands can have different colours. Explain why. Copper(and silver(salts are colourless. Suggest why. Consider the following two equilibria and associated data values at 298 K. AgBrAg++ Br –equilibrium1 Ksp = 5.0 × 10–13 mol2 dm–6 Ag++ 2NH3[Ag(NH3)2]+equilibrium2 Kstab = 1.7 × 107 mol–2 dm6 The equilibrium constant for equilibrium1 is the solubility product, Ksp, of AgBr. The equilibrium constant for equilibrium2 is the stability constant, Kstab, for the formation of [Ag(NH3)2]+. Calculate the solubility of AgBr at 298 K in mol dm–3.  solubility of AgBr = mol dm–3 Use Le Chatelier’s principle as applied to equilibria 1 and 2 to suggest why AgBrdissolves in concentrated NH3. Use equilibria1 and 2 to construct an equation for the reaction of AgBrwith concentrated NH3. This is equilibrium3. equilibrium3 Write an expression for the equilibrium constant of equilibrium 3, Keq3, in terms of Ksp for equilibrium1 and Kstab for equilibrium2. Keq3 =  Define the term standard electrode potential, E o. Complete and label the diagram to show how the standard electrode potential, E o, of Ag+/ Agcould be measured under standard conditions.  Use the Data Booklet to label the diagram in to show ● ● which is the positive electrode, ● ● the direction of electron flow in the external circuit when a current flows.  
9701_s19_qp_42
THEORY
2019
Paper 4, Variant 2
View
Aqueous solutions of copper(salts contain the blue-coloured [Cu(H2O)6]2+ complex ion. Separate portions of this blue solution react with aqueous sodium hydroxide and with concentrated hydrochloricacid. Give the following information for each of these reactions. ● ● reaction with aqueous sodiumhydroxide ionic equation type of reaction colour and state of the copper-containing product ● ● reaction with concentrated hydrochloricacid ionic equation type of reaction colour and state of the copper-containing product  Chloride ions can be identified using aqueous silvernitrate, AgNO3. Ag++ Cl –AgCl 0.303 g of a chloride of sulfur is completely hydrolysed with water. All the chlorine atoms present in the chloride of sulfur are converted into chloride ions. The solution is diluted to 100.0 cm3. A 25.00 cm3 sample of this solution is titrated with 0.0500 mol dm–3 AgNO3. The titration requires 22.40 cm3 of 0.0500 mol dm–3 AgNO3. Calculate the empirical formula of the chloride of sulfur. Show all your working.  empirical formula of chloride of sulfur = 
9701_s19_qp_43
THEORY
2019
Paper 4, Variant 3
View
An aqueous solution of cobalt(contains the [Co(H2O)6]2+ complex ion. Define the term complex ion. Samples of [Co(H2O)6]2+ are reacted separately with aqueous sodiumhydroxide and with an excess of aqueous ammonia. Give the following information about these reactions. ● ● the reaction of [Co(H2O)6]2+ with aqueous sodiumhydroxide colour and state of the cobalt-containing species ionic equation type of reaction ● ● the reaction of [Co(H2O)6]2+ with an excess of aqueous ammonia colour and state of the cobalt-containing species ionic equation type of reaction  When concentrated hydrochloricacid is added to a solution containing [Co(H2O)6]2+, a blue solution of [CoCl 4]2– is formed and the following equilibrium is established. [Co(H2O)6]2+ + 4Cl – [CoCl 4]2– + 6H2O Use Le Chatelier’s principle to suggest the expected observations when silvernitrate solution is added dropwise to the blue solution of [CoCl 4]2–. Explain your answer. The [Co(NH3)3Cl 3] complex shows stereoisomerism. Complete the three-dimensional diagrams to show the two isomers of [Co(NH3)3Cl 3]. Suggest the type of stereoisomerism. Co Co type of stereoisomerism  CompoundX, C6H18N4, is a tetradentate ligand. H2N NH2 N H X H N Suggest why one molecule of X can form four dative bonds. C6H18N4 reacts with aqueous cobalt(ions, [Co(H2O)6]2+, in a 1 : 1 ratio to form a new complex ion. Construct an equation for this reaction. 
9701_s20_qp_41
THEORY
2020
Paper 4, Variant 1
View
An aqueous solution of cobalt(contains the [Co(H2O)6]2+ complex ion. Define the term complex ion. Samples of [Co(H2O)6]2+ are reacted separately with aqueous sodiumhydroxide and with an excess of aqueous ammonia. Give the following information about these reactions. ● ● the reaction of [Co(H2O)6]2+ with aqueous sodiumhydroxide colour and state of the cobalt-containing species ionic equation type of reaction ● ● the reaction of [Co(H2O)6]2+ with an excess of aqueous ammonia colour and state of the cobalt-containing species ionic equation type of reaction  When concentrated hydrochloricacid is added to a solution containing [Co(H2O)6]2+, a blue solution of [CoCl 4]2– is formed and the following equilibrium is established. [Co(H2O)6]2+ + 4Cl – [CoCl 4]2– + 6H2O Use Le Chatelier’s principle to suggest the expected observations when silvernitrate solution is added dropwise to the blue solution of [CoCl 4]2–. Explain your answer. The [Co(NH3)3Cl 3] complex shows stereoisomerism. Complete the three-dimensional diagrams to show the two isomers of [Co(NH3)3Cl 3]. Suggest the type of stereoisomerism. Co Co type of stereoisomerism  CompoundX, C6H18N4, is a tetradentate ligand. H2N NH2 N H X H N Suggest why one molecule of X can form four dative bonds. C6H18N4 reacts with aqueous cobalt(ions, [Co(H2O)6]2+, in a 1 : 1 ratio to form a new complex ion. Construct an equation for this reaction. 
9701_s20_qp_43
THEORY
2020
Paper 4, Variant 3
View
Explain why chromium complexes are coloured. Four different compounds can be obtained when anhydrous chromium(chloride reacts with water under various conditions. When samples of each compound are reacted separately with aqueous silvernitrate, different amounts of silverchloride are precipitated. The precipitation leaves the complex ions P, Q, R and S in solution. formula of compound moles of AgCl precipitated per mole of complex ion complex ion property of complex ion CrCl 3(H2O)6 P non-polar CrCl 3(H2O)5 Q polar CrCl 3(H2O)4 R polar CrCl 3(H2O)4 S non-polar Draw three-dimensional diagrams for the structures of complex ions P, Q, R and S. Include the charges for each complex ion. P Cr Q Cr R Cr S Cr  Suggest why complex ion S is non-polar. The structure of picolinicacid is shown. picolinic acid CO2H N The conjugate base of picolinicacid is a bidentate ligand, Z. Define the term bidentate ligand. Draw the structure of Z.  Z reacts with aqueous chromium(ions, [Cr(H2O)6]3+, in a 3 : 1 ratio to form a new neutral complex. State the coordination number and the geometry of the chromium(centre in the complex. coordination number geometry ����������������������������������������� (NH4)2Cr2O7 decomposes readily on heating to form Cr2O3, steam and an inert colourless gas. Deduce the oxidation numbers of chromium in (NH4)2Cr2O7 and in Cr2O3. (NH4)2Cr2O7 Cr2O3 ��������������������������������������������������� Construct an equation for the thermal decomposition of (NH4)2Cr2O7. 
9701_s21_qp_41
THEORY
2021
Paper 4, Variant 1
View
Define the term transition element. State how the melting point and density of iron compare to those of calcium. Define the term standard cell potential, . Draw a fully labelled diagram of the apparatus that can be used to measure the cell potential of a cell composed of a Cu(/Cu electrode and an Fe(/Fe(electrode. Include all necessary reactants.  The reaction between S2O8 2–and I –is catalysed by adding a few drops of Fe3+. Use equations to show the catalytic role of Fe3+ in this reaction.  Fe3+can oxidise I –, whereas [Fe(CN)6]3–cannot oxidise I –. Use E o values to explain these observations. When aqueous solutions of S2O8 2– and tartrate ions are mixed the reaction proceeds very slowly. However, this reaction proceeds quickly in the presence of an Fe3+catalyst. The overall equation for this reaction is shown. tartrate ions + 3S2O8 2– + 2H2O 2CO2 + 2HCO2 – + 6H+ + 6SO4 2– OH OH CO2 – –O2C Suggest why this reaction is slow without the Fe3+ catalyst. Use the overall equation to deduce the half-equation for the oxidation of tartrate ions, C4H4O6 2–, to carbondioxide, CO2, and methanoate ions, HCO2 –. C4H4O6 2– +  Complete the following table to show the structures of the organic products formed when tartaric acid reacts separately with each reagent. Identify each type of reaction. tartaric acid OH OH CO2H HO2C reagent structure of organic product type of reaction an excess of LiAl H4 an excess of CH3COCl  Tartaric acid reacts with the amine 1-phenylethylamine, C6H5CH(NH2)CH3, to form an ionicsalt. Draw the structure of the salt formed in this reaction. Include the charges on the ions.  
9701_s21_qp_41
THEORY
2021
Paper 4, Variant 1
View
Questions Discovered
171