Developing Metals

What Developing Metals covers

The storyline that carries electrochemistry and the transition elements: redox titrations, balancing half-equations in acid, electrochemical cells and standard electrode potentials, rusting, and the complexes, colours and catalysis of the d-block.

The 18 subtopics

Each one has its own page.

• Manganate(VII) titrations and their calculationsRecall questions on why manganate(VII) is self-indicating, which acid is used and why the others are not, and the calculations with iron(II), ethanedioate and peroxide.Open →
• Thiosulfate titrations, recording results and good techniqueRecall questions on the copper(II) and iodine route, when starch is added, concordant titres, and why the burette but not the flask is rinsed with solution.Open →
• Shapes of complexes and coordination numberRecall questions on why coordination number is not always the ligand count, and the shapes and bond angles for four and six coordination.Open →
• Balancing redox equations involving acid-base reactionsRecall questions on the manganate(VII) and dichromate(VI) half-equations, why the electron counts are what they are, and combining halves into a full equation.Open →
• Simple electrochemical cellsRecall questions on setting up a metal half-cell, the salt bridge, the high-resistance voltmeter, and the standard conditions.Open →
• Action of an electrochemical cellRecall questions on which electrode is negative and why, the half-equation at each, and what happens to the electrode masses and the solution as the cell runs.Open →
• Standard electrode potentials and calculating E°cellRecall questions on the definition and the hydrogen reference, what a positive or negative value means, and calculating E°cell to test feasibility.Open →
• Rusting and how it is preventedRecall questions on the two half-equations, what rust is, and how galvanising, barrier methods and cathodic protection each work.Open →
• Transition metals: definition, oxidation states and coloursRecall questions on what defines a transition element, the colours of the common aqueous ions, and the disproportionation of copper(I).Open →
• d-block electron configurations of the atoms and their ionsRecall questions on which sub-shell fills first, which electrons are lost first, and the configurations of chromium, copper and the common ions.Open →
• Why transition metals show variable oxidation statesRecall questions on the closeness of the 4s and 3d energies, why the s-block shows one state only, and which arrangements carry extra stability.Open →
• Ligands and complex ionsRecall questions on the three common monodentate ligands, why complexes carry the charges they do, and working out a complex's charge.Open →
• Coordinate bonding and what makes a ligandRecall questions on what a coordinate bond is, which atom donates, why methane cannot be a ligand, and how the bond compares with an ordinary covalent one.Open →
• Bidentate and multidentate ligands, and finding a complex's formulaRecall questions on the ethanedioate ion and EDTA, how many bind to one metal ion, and deducing a formula from a mole ratio.Open →
• Reactions of Fe2+, Fe3+ and Cu2+ with hydroxide and ammoniaRecall questions on the colour and identity of each precipitate, the ionic equations, why the iron(II) precipitate darkens, and which redissolve in excess ammonia.Open →
• Catalytic activity of transition metalsRecall questions on how a variable oxidation state allows catalysis, the two steps of the iodide and peroxodisulfate route, and adsorption strength.Open →
• Origin of colour in transition metal complexesRecall questions on d orbital splitting, why some ions are colourless, and how ligand, oxidation state and coordination number change the colour.Open →
• ColorimetryRecall questions on choosing a filter, the blank, building and using a calibration line, and why a sample above the range must be diluted.Open →

What you need to know

Answer each one before you reveal it.

Take Developing Metals further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• Ligand vs Coordination number

  Ligand: a species donating a lone pair to form a coordinate bond with a metal ion. Coordination number: the number of coordinate bonds formed to the central metal ion.

• Monodentate ligand vs Bidentate ligand

  Monodentate ligand: a ligand that forms one coordinate bond to the metal ion. Bidentate ligand: a ligand that forms two coordinate bonds to the same metal ion.

• Standard electrode potential vs Standard cell potential

  Standard electrode potential: the potential of a half-cell measured against the standard hydrogen electrode. Standard cell potential: the difference between the two electrode potentials of a complete cell.

Questions from this topic

Each one with the model answer underneath.

1. 1

   What is the oxidising agent in a manganate(VII) titration, and what is the oxidation state of the manganese in it?

   Model answer

   The manganate(VII) ion MnO₄⁻ is the oxidising agent, and the manganese in it has oxidation state +7.

2. 2

   Why does a manganate(VII) titration need no added indicator?

   Model answer

   MnO₄⁻ is intensely purple while Mn²⁺ is almost colourless, so the reagent indicates its own end point.

3. 3

   Describe what you see at the end point when MnO₄⁻ is run into acidified iron(II) solution.

   Model answer

   The flask stays colourless or very pale until one drop gives a permanent faint pink colour.

4. 4

   Which acid is used to acidify a manganate(VII) titration, and why is hydrochloric acid avoided?

   Model answer

   Dilute sulfuric acid is used, because manganate(VII) would oxidise the chloride ions of hydrochloric acid and the titre would be too large.

5. 5

   Why is nitric acid also unsuitable for acidifying a manganate(VII) titration?

   Model answer

   Nitric acid is itself an oxidising agent, so it would oxidise some of the reducing agent being measured and give a titre that is too small.

6. 6

   State the ionic equation for the reaction of manganate(VII) with iron(II) ions in acid solution.

   Model answer

   The equation is MnO₄⁻ + 5Fe²⁺ + 8H⁺ → Mn²⁺ + 5Fe³⁺ + 4H₂O.

What is inside Levo

Six ways to work the same material.

Developing Metals revision questions

What does Developing Metals cover in OCR A-Level Chemistry B?

18 subtopics: manganate(vii) titrations and their calculations, thiosulfate titrations, recording results and good technique, shapes of complexes and coordination number, balancing redox equations involving acid-base reactions, simple electrochemical cells, action of an electrochemical cell, standard electrode potentials and calculating e°cell, rusting and how it is prevented, transition metals: definition, oxidation states and colours, d-block electron configurations of the atoms and their ions, why transition metals show variable oxidation states, ligands and complex ions, coordinate bonding and what makes a ligand, bidentate and multidentate ligands, and finding a complex's formula, reactions of fe2+, fe3+ and cu2+ with hydroxide and ammonia, catalytic activity of transition metals, origin of colour in transition metal complexes and colorimetry. Each one has its own page with questions and model answers.

How is Developing Metals organised?

By the OCR H433 specification, subtopic by subtopic, so it matches the order you are taught it in.