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
Organic Chemistry III
Empirical and molecular formulae from analytical data
- 3 things to know
- Papers 2 and 3
Overview
Empirical formulae from combustion analysis and from percentage composition, the molecular formula from the relative molecular mass, and what functional group tests, infrared spectra, mass spectra and NMR each contribute to identifying an unknown compound.
What you need to know
Answer each one before you reveal it.
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Key term
When determining empirical formula from percentage composition, what is the first step for each element?
Key term
From combustion analysis data, how is the number of moles of hydrogen in the original compound found?
Questions from this subtopic
Each one with the model answer underneath.
- 1
In combustion analysis, how do you determine the number of moles of carbon in the original compound?
Model answer
Calculate the moles of CO₂ produced, since each mole of CO₂ contains exactly one mole of carbon.
- 2
From combustion analysis data, how is the number of moles of hydrogen in the original compound found?
Model answer
Calculate the moles of H₂O produced and multiply by 2, since each mole of H₂O contains two moles of hydrogen atoms.
- 3
When deducing the empirical formula of an oxygen-containing compound from combustion analysis, how are the moles of oxygen determined?
Model answer
By difference: subtract the mass of carbon and hydrogen from the total mass of the compound, then convert the remaining mass to moles of oxygen.
- 4
After calculating moles of C, H, and O from combustion analysis, what mathematical step gives the empirical formula?
Model answer
Divide all mole values by the smallest value to obtain the simplest whole number ratio of atoms.
- 5
When determining empirical formula from percentage composition, what is the first step for each element?
Model answer
Divide the percentage of each element by its relative atomic mass to obtain a molar ratio.
- 6
After dividing percentages by relative atomic masses, how do you proceed to find the empirical formula?
Model answer
Divide all the resulting values by the smallest value to give a ratio.
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