Key term
Edexcel A-Level Chemistry 9CH0
Atomic Structure and the Periodic Table
Bonding and Structure
Inorganic Chemistry and the Periodic Table
Topic overviewFlame tests and how they workThermal decomposition of nitrates and carbonatesCarrying out flame tests and testing the gasesGroup 2 elements and their compoundsTrends in Group 7 and predicting fluorine and astatineHalogen displacement reactionsDisproportionation and the reactions of chlorineHalides with concentrated sulfuric acid, and the hydrogen halidesTesting for halide ions with silver nitrateTesting for carbonate and hydrogencarbonate ionsTesting for sulfate and ammonium ions
Formulae, Equations and Amounts of Substance
Topic overviewThe mole, molar mass and empirical formulaThe ideal gas equation and molar volumeEquations, concentration and reacting quantitiesStandard solutions, titration and uncertaintyPercentage yield, atom economy and acid reactionsCore practicals 1 to 3Empirical formula and water of crystallisation by experimentApparatus, uncertainty and mathematical skills
Organic Chemistry I
Topic overviewFormulae, homologous series and functional groupsIUPAC nomenclatureTypes of organic reaction and structural isomerismStereoisomerism and E/Z nomenclaturePractical techniques in organic chemistryAlkanes, crude oil and combustion pollutantsRadical substitutionAlkenes, the double bond and hydrogenationElectrophilic addition, Markovnikov's rule and the test for an alkeneAddition polymers and waste polymersNucleophilic substitution of halogenoalkanesRates of hydrolysis and the SN1 and SN2 mechanismsClassifying and oxidising alcoholsAlcohols: practical techniques and the core practicals
Modern Analytical Techniques I
Energetics I
Kinetics I
Equilibrium I
Acid-Base Equilibria
Energetics II
Redox II
Transition Metals
Topic overviewElectron configuration and what makes a transition metalComplex ions, ligands and the colour of transition metal ionsCoordination number, monodentate ligands and the shapes of complexesBidentate and multidentate ligands, and ligand exchangeVanadium and chromium chemistryReactions with sodium hydroxide and ammoniaCobalt and copper complexesLigand exchange, amphoteric behaviour and the chelate effectTransition metals as catalysts
Kinetics II
Organic Chemistry II
Topic overviewChiralityAldehydes, ketones and their oxidationReduction and nucleophilic addition of HCNTesting for a carbonyl group: 2,4-DNPH and the iodoform reactionCarboxylic acids and their reactionsEsters and acyl chloridesReflux, extraction and recrystallisationDistillation, melting temperature and working safely
Organic Chemistry III
Topic overviewThe structure of benzene and the evidence for itElectrophilic substitution of benzeneNitration, halogenation, Friedel-Crafts and phenolAmines: structure and basicityReactions of amines and preparing themAmides and condensation polymersAmino acids, zwitterions and proteinsEmpirical and molecular formulae from analytical dataGrignard reagents and multi-step synthesisPurification techniques and the aspirin preparation
Transition Metals
Reactions with sodium hydroxide and ammonia
- 3 things to know
- Papers 1 and 3
Overview
The hydroxide precipitates Cr³⁺, Fe²⁺, Fe³⁺ and Co²⁺ give with sodium hydroxide and ammonia and which dissolve in excess, the oxidation of Fe(OH)₂ in air, and Core Practical 12 preparing tetraamminecopper(II) sulfate, with its purpose, equation, method, safety and yield.
What you need to know
Answer each one before you reveal it.
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Process
Describe what happens when excess aqueous ammonia is added to a solution of Fe³⁺(aq).
Key term
What is observed when dilute NaOH is added to a solution containing Cr³⁺ ions?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is observed when dilute NaOH is added to a solution containing Cr³⁺ ions?
Model answer
A grey-green precipitate of Cr(OH)₃ forms.
- 2
What happens when excess NaOH is added to Cr³⁺(aq), and what does this demonstrate?
Model answer
The precipitate dissolves to form a dark green solution containing [Cr(OH)₆]³⁻, demonstrating amphoteric behaviour.
- 3
What is observed when dilute ammonia is added to Cr³⁺(aq)?
Model answer
A grey-green precipitate of Cr(OH)₃ forms.
- 4
What happens when excess ammonia is added to the precipitate formed from Cr³⁺(aq) and dilute NH₃?
Model answer
The precipitate dissolves to form a purple solution containing [Cr(NH₃)₆]³⁺, by ligand exchange.
- 5
What is observed when dilute NaOH is added to Fe²⁺(aq)?
Model answer
A green precipitate of Fe(OH)₂ forms.
- 6
What happens when excess NaOH is added to the precipitate formed from Fe²⁺(aq)?
Model answer
No change; the green precipitate remains.
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