Unit 5: Transition Metals and Organic Nitrogen Chemistry
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Topic 16: Redox Equilibria
Understand the terms ‘oxidation’ and ‘reduction’ in terms of electron transfer and changes in oxidation number, applied to s-, p- and d-block elements
Know what is meant by the term ‘standard electrode potential’, Eo
Know that the standard electrode potential, Eo, is measured in conditions of: i 298 K temperature ii 100 kPa pressure of gases iii 1.00 mol dm-3 concentration of ions
Know the features of the standard hydrogen electrode and understand why a reference electrode is necessary
Understand that different methods are used to measure standard electrode potentials of: i metals or non-metals in contact with their ions in aqueous solution ii ions of the same element with different oxidation numbers
CORE PRACTICAL 12 Investigating some electrochemical cells.
Be able to calculate a standard emf, Eocell , by combining two standard electrode potentials
Be able to write cell diagrams using the conventional representation of half-cells
Understand the importance of the conditions when measuring an electrode potential, E
Be able to use standard electrode potentials to predict the thermodynamic feasibility of a reaction
Understand that Eocell is directly proportional to the total entropy change and to lnK for a reaction
Understand the limitations of predictions made using standard electrode potentials, in terms of kinetic stability of systems and departure from standard conditions
Know that standard electrode potentials are sometimes referred to as standard reduction potentials and can be listed as an electrochemical series
Understand how standard electrode potentials can be used to predict the thermodynamic feasibility of disproportionation reactions
Be able to carry out both structured and unstructured titration calculations involving redox reactions, including iron(II) ions and potassium manganate(VII) and sodium thiosulfate and iodine
Be able to discuss the uncertainty of measurements and their implications for the validity of the final results
CORE PRACTICALS 13a and 13b Carry out redox titrations with both: i iron(II) ions and potassium manganate(VII) ii sodium thiosulfate and iodine
Understand that fuel cells use the energy released on the reaction of a fuel with oxygen to generate a voltage Knowledge that methanol and other hydrogen-rich fuels are used in fuel cells is expected.
Know the electrode reactions that occur in a hydrogen-oxygen fuel cell Knowledge of hydrogen-oxygen fuel cells with both acidic and alkaline electrolyte is expected.
Topic 17: Transition Metals and their Chemistry
17.1Transition metals are d-block elements that form one or more stable ions with incompletely-filled d-orbitals
Know that transition metals are d-block elements that form one or more stable ions with incompletely-filled d-orbitals
17.2Deduce the electronic configurations of atoms and ions of the d-block elements of Period 4 (Sc-Zn) given their atomic number
Be able to deduce the electronic configurations of atoms and ions of the d-block elements of Period 4 (Sc-Zn) given their atomic number and charge (if any)
17.3Why transition metals show variable oxidation number
Understand why transition metals show variable oxidation number
17.4What is meant by the term ‘ligand’
Know what is meant by the term ‘ligand’
17.5Dative (coordinate) covalent bonding is involved in the formation of complex ions
Understand that dative (coordinate) covalent bonding is involved in the formation of complex ions
17.6A complex ion is a central metal ion surrounded by ligands
Know that a complex ion is a central metal ion surrounded by ligands
17.7Aqueous solutions of transition metal ions are usually coloured
Know that aqueous solutions of transition metal ions are usually coloured
17.8The colour of aqueous ions, and other complex ions, is a consequence of the splitting of the energy levels of the d-orbitals
Understand that the colour of aqueous ions, and other complex ions, is a consequence of the splitting of the energy levels of the d-orbitals by ligands
17.9Why there is a lack of colour in some aqueous ions and other complex ions
Understand why there is a lack of colour in some aqueous ions and other complex ions
17.10The meaning of the term ‘coordination number’
Understand the meaning of the term ‘coordination number’
17.11Colour changes in transition metal ions may arise as a result of changes in: i oxidation number of the ion ii ligand iii
Understand that colour changes in transition metal ions may arise as a result of changes in: i oxidation number of the ion ii ligand iii coordination number of the complex
17.12H2O, OH- and NH3 act as monodentate ligands
Understand that H2O, OH- and NH3 act as monodentate ligands
17.13Why complexes with six-fold coordination have an octahedral shape, such as those formed by metal ions with H2O, OH- and NH3
Understand why complexes with six-fold coordination have an octahedral shape, such as those formed by metal ions with H2O, OH- and NH3 as ligands
17.14Transition metal ions may form tetrahedral complexes with relatively large ions such as Cl-
Know that transition metal ions may form tetrahedral complexes with relatively large ions such as Cl-
17.15Square planar complexes are also formed by transition metal ions and that cis-platin is an example of such a complex which
Know that square planar complexes are also formed by transition metal ions and that cis-platin is an example of such a complex which is used in cancer treatment where it is supplied as a single isomer and not in a mixture with the trans form
17.16The terms ‘bidentate’ and ‘hexadentate’ in relation to ligands
Understand the terms ‘bidentate’ and ‘hexadentate’ in relation to ligands, and be able to identify examples such as NH2CH2CH2NH2 and EDTA4-
17.17Haemoglobin is an iron(II) complex containing a polydentate ligand and that ligand exchange occurs when an oxygen molecule
Know that haemoglobin is an iron(II) complex containing a polydentate ligand and that ligand exchange occurs when an oxygen molecule bound to haemoglobin is replaced by a carbon monoxide molecule The structure of the haem group will not be assessed.
17.18The colours of the oxidation states of vanadium (+5, +4, +3 and +2) in its compounds
Know the colours of the oxidation states of vanadium (+5, +4, +3 and +2) in its compounds
17.19Redox reactions for the interconversion of the oxidation states of vanadium (+5, +4, +3 and +2), in terms of the relevant Eo
Understand redox reactions for the interconversion of the oxidation states of vanadium (+5, +4, +3 and +2), in terms of the relevant Eo values
17.20Understand, in terms of the relevant E values, that the dichromate(VI) ion, Cr2O2- i can be reduced to Cr3+ and Cr2+ ions
Understand, in terms of the relevant E values, that the dichromate(VI) ion, Cr2O2- i can be reduced to Cr3+ and Cr2+ ions using zinc in acidic conditions ii can be produced by the oxidation of Cr3+ ions using hydrogen peroxide in alkaline conditions (followed by acidification)
17.21Dichromate(VI) ions can be converted into chromate(VI) ions through the equilibrium Cr2O7^2− + H2O ⇌ 2CrO4^2− + 2H+
Know that dichromate(VI) ions can be converted into chromate(VI) ions through the equilibrium Cr2O7^2− + H2O ⇌ 2CrO4^2− + 2H+.
17.22Record observations and write suitable equations for the reactions of Cr3+(aq), Mn2+(aq), Fe2+(aq), Fe3+(aq), Co2+(aq)
Be able to record observations and write suitable equations for the reactions of Cr3+(aq), Mn2+(aq), Fe2+(aq), Fe3+(aq), Co2+(aq), Ni2+(aq), Cu2+(aq) and Zn2+(aq) with aqueous sodium hydroxide and aqueous ammonia, including in excess
17.23Write ionic equations to show the meaning of amphoteric behaviour, deprotonation and ligand exchange in the reactions
Be able to write ionic equations to show the meaning of amphoteric behaviour, deprotonation and ligand exchange in the reactions in 17.22
17.24Ligand exchange, and an accompanying colour change, occurs in the formation of: i [Cu(NH3)4(H2O)2]2+ from [Cu(H2O)6]2+ via
Understand that ligand exchange, and an accompanying colour change, occurs in the formation of: i [Cu(NH3)4(H2O)2]2+ from [Cu(H2O)6]2+ via Cu(OH)2(H2O)4 ii [CuCl4]2- from [Cu(H2O)6]2+ iii [CoCl4]2- from [Co(H2O)6]2+
17.25Understand, in terms of the positive increase in ∆Ssystem, that the substitution of a monodentate ligand by a bidentate or
Understand, in terms of the positive increase in ∆Ssystem, that the substitution of a monodentate ligand by a bidentate or hexadentate ligand leads to a more stable complex ion
17.26Transition metals and their compounds can act as heterogeneous and homogeneous catalysts
Know that transition metals and their compounds can act as heterogeneous and homogeneous catalysts
17.27A heterogeneous catalyst is in a different phase from the reactants and that the reaction occurs at the surface of
Know that a heterogeneous catalyst is in a different phase from the reactants and that the reaction occurs at the surface of the catalyst
17.28Understand, in terms of oxidation number, how V2O5 acts as a catalyst in the contact process
Understand, in terms of oxidation number, how V2O5 acts as a catalyst in the contact process
17.29How a catalytic converter decreases carbon monoxide and nitrogen monoxide emissions from internal combustion engines by: i
Understand how a catalytic converter decreases carbon monoxide and nitrogen monoxide emissions from internal combustion engines by: i adsorption of CO and NO molecules onto the surface of the catalyst, resulting in the weakening of bonds and chemical reaction ii desorption of CO2 and N2 product molecules from the surface of the catalyst
17.30A homogeneous catalyst is in the same phase as the reactants and appreciate that the catalysed reaction will proceed via
Know that a homogeneous catalyst is in the same phase as the reactants and appreciate that the catalysed reaction will proceed via an intermediate species
17.31The role of Fe2+ ions in catalysing the reaction between I− and S2O8^2− ions
Understand the role of Fe2+ ions in catalysing the reaction between I− and S2O8^2− ions.
17.32The role of Mn2+ ions in autocatalysing the reaction between MnO4− and C2O4^2− ions
Know the role of Mn2+ ions in autocatalysing the reaction between MnO4− and C2O4^2− ions.
17.33CORE PRACTICAL 14 The preparation of a transition metal complex
CORE PRACTICAL 14 The preparation of a transition metal complex.
Topic 18: Organic Chemistry – Arenes
Be able to use thermochemical, X-ray diffraction and infrared data as evidence for the structure and stability of the benzene ring Students may represent the structure of benzene as or as appropriate in equations and mechanisms.
Understand that the delocalised model for the structure of benzene involves overlap of p-orbitals to form π-bonds
Understand why benzene is resistant to bromination, compared to alkenes, in terms of delocalisation of π-bonds in benzene compared to the localised electron density of the π-bond in alkenes
Know the following reactions of benzene, limited to: i oxygen in air (combustion to form a smoky flame) ii bromine, in the presence of a catalyst iii a mixture of concentrated nitric and sulfuric acids iv fuming sulfuric acid v halogenoalkanes and acyl chlorides with aluminium chloride as catalyst (Friedel-Crafts reaction)
Understand the mechanism of the electrophilic substitution reactions of benzene in halogenation, nitration and Friedel-Crafts reactions, including the generation of the electrophile
Understand the reaction of phenol with bromine water and the reasons for the relative ease of this reaction compared to benzene
Topic 19: Organic Nitrogen Compounds: Amines, Amides, Amino Acids and Proteins
Understand the nomenclature of amides, amines and amino acids and be able to draw their structural, displayed and skeletal formulae
Understand the reactions of primary aliphatic amines (using butylamine as an example) and aromatic amines (using phenylamine as an example) with: i water to form an alkaline solution ii acids to form salts iii halogenoalkanes iv ethanoyl chloride v copper(II) ions to form a complex ion
Understand that amines are miscible with water as a result of hydrogen bonding, and the reasons for the difference in basicity between ammonia, primary aliphatic amines and primary aromatic amines
Understand, in terms of reagents and general reaction conditions, the preparation of primary aliphatic amines: i from halogenoalkanes ii by the reduction of nitriles
Know the preparation of aromatic amines by the reduction of aromatic nitro- compounds using tin and concentrated hydrochloric acid
Be able to describe the reaction of aromatic amines with nitrous acid to form benzenediazonium ions, followed by a coupling reaction with phenol to form a dye
Understand that amides can be prepared from acyl chlorides
Be able to describe: i condensation polymerisation for the formation of polyamides such as nylon and proteins ii addition polymerisation, including poly(propenamide) and poly(ethenol)
Be able to draw the structural formulae of the repeat units of the polymers in 19.8
Be able to comment on the physical properties of polyamides and the solubility in water of the addition polymer poly(ethenol) in terms of hydrogen bonding, including soluble laundry bags or liquid-detergent capsules (liquitabs)
Be able to describe experiments to investigate the characteristic behaviour of amino acids limited to: i acidity and basicity and the formation of zwitterions ii effect of aqueous solutions on plane-polarised monochromatic light iii formation of peptide bonds by condensation polymerisation
CORE PRACTICAL 15 Analysis of some inorganic and organic unknowns.
Topic 20: Organic Synthesis
Be able to deduce the empirical formulae, molecular formulae and structural formulae from data drawn from combustion analysis, element percentage composition, characteristic reactions of functional groups, infrared spectra, mass spectra and NMR spectra (both 13C and proton)
Understand methods of increasing the length of the carbon chain in a molecule by the use of magnesium to form Grignard reagents and the reactions of the latter with carbon dioxide and with carbonyl compounds in dry ether
Be able to use knowledge of organic chemistry contained given in this specification to solve problems such as: i predicting the properties of unfamiliar compounds containing one or more of the functional groups included in the specification and explain these predictions ii planning reaction schemes of up to four steps, recalling familiar reactions and using unfamiliar reactions given sufficient information iii selecting suitable practical procedures for carrying out reactions involving compounds with functional groups included in this specification iv identifying appropriate control measures to reduce risk based on data of hazards
CORE PRACTICAL 16 The preparation of aspirin.
Understand the following techniques used in the preparation and purification of organic compounds: i refluxing ii purification by washing, including with water and sodium carbonate solution iii solvent extraction iv recrystallisation v drying vi distillation vii steam distillation viii melting temperature determination ix boiling temperature determination