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
Formulae, Equations and Amounts of Substance
Empirical formula and water of crystallisation by experiment
- 3 things to know
- Papers 1, 2 and 3
Overview
Finding an empirical formula by heating a substance in a crucible to constant mass, defining water of crystallisation, and finding x in a hydrated salt by heating, cooling and reweighing to constant mass and comparing the moles of anhydrous salt and water.
What you need to know
Answer each one before you reveal it.
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Key term
After achieving constant mass, how is the empirical formula determined?
Process
When determining empirical formula experimentally, what are the first two steps involving the crucible?
Questions from this subtopic
Each one with the model answer underneath.
- 1
When determining empirical formula experimentally, what are the first two steps involving the crucible?
Model answer
Weigh the crucible and lid, then add the substance and reweigh.
- 2
What is done to the substance in the crucible when determining empirical formula?
Model answer
Heat strongly to complete the reaction.
- 3
After heating the substance in the crucible, what must be done before reweighing?
Model answer
Cool the crucible and contents.
- 4
Why is heating repeated when determining empirical formula experimentally?
Model answer
To ensure constant mass is achieved, indicating the reaction is complete.
- 5
After achieving constant mass, how is the empirical formula determined?
Model answer
Calculate masses of each element, convert to moles, and determine the simplest whole number ratio.
- 6
Define water of crystallisation.
Model answer
Water of crystallisation is water molecules incorporated into the crystal structure of a salt.
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