Process
AQA A-Level Chemistry 7405
Atomic Structure
Topic overviewFundamental ParticlesMass Number and IsotopesTime of Flight Mass Spectrometry: Ionisation and AccelerationTime of Flight Mass Spectrometry: Drift, Detection and Calculating m/zElectron Configuration: Sub-shells and OrbitalsElectron Configuration: Writing Configurations for Atoms and IonsIonisation Energies and Periodic Trends
Amount of Substance
Topic overviewRelative Atomic and Molecular MassThe Mole and the Avogadro ConstantThe Ideal Gas EquationEmpirical and Molecular FormulaBalanced Equations and Reaction CalculationsAtom Economy and Percentage YieldAcid-Base Titrations: Principles, Indicators and ApparatusAcid-Base Titrations: Standard Solutions and Calculations
Bonding
Topic overviewIonic BondingCovalent, Dative Covalent and Metallic BondingCrystal Structures: Giant Ionic Lattices and DiamondCrystal Structures: Graphite and Simple Molecular SolidsShapes of Molecules and Ions: VSEPR and Electron Pair RepulsionShapes of Molecules and Ions: Predicting Shapes and Bond AnglesElectronegativity and Bond PolarityIntermolecular Forces
Energetics and Thermodynamics
Kinetics
Topic overviewCollision Theory and Activation EnergyMaxwell-Boltzmann Distribution and the Effect of TemperatureEffect of Concentration and Pressure, and CatalystsRate Equations: The Rate Equation and Orders of ReactionRate Equations: The Effect of Concentration on RateThe Rate Constant and the Arrhenius EquationDetermining Rate Equations: The Initial Rates MethodDetermining Rate Equations: Continuous MonitoringRate Equations and Reaction Mechanisms
Chemical Equilibria
Redox and Electrochemistry
Topic overviewRedox: Definitions and the Rules for Oxidation StatesRedox: Identifying Oxidation and Reduction in a ReactionHalf-Equations and Combined Redox EquationsStandard Electrode Potentials and the Hydrogen ElectrodeElectrochemical Cells and EMF CalculationsPredicting Redox Reactions from Electrode PotentialsCommercial Cells and Fuel Cells
Acids and Bases
Periodicity and Group Chemistry
Topic overviews, p, d and f Block ClassificationTrends in Period 3Group 2 Trends in Atomic Radius, Ionisation Energy and Melting PointReactions of Group 2 with WaterSolubility Trends of Group 2 HydroxidesSolubility Trends of Group 2 SulfatesUses of Group 2 CompoundsTest for Sulfate IonsTrends in Electronegativity and Boiling Point of HalogensHalogens as Oxidising Agents and Displacement ReactionsHalide Ions as Reducing Agents: Chloride and BromideHalide Ions as Reducing Agents: Iodide, and the EquationsTest for Halide Ions Using Silver NitrateTests for Ammonium, Group 2, Hydroxide and Carbonate IonsReactions of Chlorine with WaterReactions of Chlorine with Cold Dilute NaOH and Water Treatment
Period 3 Elements and Their Oxides
Topic overviewReactions of Na and Mg with WaterPeriod 3 Elements with Oxygen: The Oxides Formed and Their BondingPeriod 3 Elements with Oxygen: Structures and Oxidation StatesMelting Points of Period 3 OxidesPeriod 3 Oxides with Water: Sodium and Magnesium OxidesPeriod 3 Oxides with Water: The Acidic Oxides and the pH TrendPeriod 3 Oxides with Acids and Bases: The ReactionsPeriod 3 Oxides with Acids and Bases: Acidic, Basic and Amphoteric
Transition Metals
Topic overviewGeneral Properties of Transition MetalsComplex Ions: Ligands, Coordinate Bonds and DenticityComplex Ions: Why a Species Can Act as a Ligand, and Coordination NumberSubstitution Reactions with Monodentate LigandsSubstitution Reactions with Bidentate and Multidentate LigandsHaemoglobin and the Chelate EffectShapes of Complex Ions and StereoisomerismFormation of Coloured Ions and the d-d TransitionColorimetry and Concentration DeterminationVariable Oxidation States and Vanadium ChemistryTollens' Reagent and Redox TitrationsHeterogeneous CatalysisVanadium(V) Oxide and the Contact ProcessHomogeneous Catalysis and AutocatalysisMetal-Aqua Ions and AcidityMetal Aqua Ions with Bases: Reactions with Hydroxide and AmmoniaMetal Aqua Ions with Bases: Why They React, and Their EquationsAmphoteric HydroxidesIdentifying Transition Metal Ions by Test-Tube Reactions
Introduction to Organic Chemistry
Hydrocarbons
Topic overviewAlkanes, Fractional Distillation and CrackingCombustion of Alkanes and PollutantsFree Radical Chlorination of AlkanesAlkenes: Structure, Bonding and Electrophilic AdditionMarkovnikov's Rule and Carbocation StabilityAddition Polymers and Repeating UnitsProperties and Uses of Polyalkenes
Halogenoalkanes, Alcohols and Organic Analysis
Topic overviewNucleophilic Substitution of HalogenoalkanesEffect of Bond Enthalpy on Reaction RateElimination Reactions and Competing MechanismsCFCs and Ozone DepletionIndustrial Production of AlcoholsBiofuels and Carbon NeutralityClassification and Oxidation of AlcoholsDistinguishing Aldehydes and KetonesElimination of Water from AlcoholsTest-Tube Reactions for Functional GroupsMass Spectrometry and Molecular FormulaInfrared Spectroscopy, Functional Groups and Global Warming
Carbonyls, Carboxylic Acids and Derivatives
Topic overviewOxidation of Aldehydes and Distinguishing TestsReduction of Carbonyls with NaBH4Nucleophilic Addition with KCN and Hydroxynitrile FormationHazards of KCN and Formation of EnantiomersStructure and Acidity of Carboxylic AcidsEsterification and the Uses of EstersVegetable Oils, Fats and the Hydrolysis of EstersSoap and Biodiesel Production from FatsStructure of Acid Anhydrides, Acyl Chlorides and AmidesNucleophilic Addition-Elimination Reactions of Acyl ChloridesAcid Anhydrides and the Industrial Synthesis of AspirinPurifying organic solids and liquids
Aromatic Chemistry and Amines
Topic overviewBonding and Stability of BenzeneElectrophilic Substitution: NitrationElectrophilic Substitution: Friedel-Crafts AcylationPreparation of Aliphatic and Aromatic AminesBase Strength of AminesAmines as Nucleophiles, and Quaternary Ammonium SaltsAmines with Acyl Chlorides and Acid Anhydrides
Polymers, Amino Acids, Proteins and DNA
Topic overviewCondensation Polymers: PolyestersCondensation Polymers: PolyamidesIntermolecular Forces in Condensation PolymersBiodegradability and Disposal of PolymersAmino Acids and ZwitterionsPeptide Bonds and Protein StructureHydrogen Bonding and Disulfide Bridges in ProteinsHydrolysis of Proteins and TLC IdentificationEnzymes, Active Sites and Inhibitors in Drug DesignDNA: Nucleotides, the Double Helix and Base PairingCisplatin and Anticancer Drug Action
Organic Synthesis, NMR and Chromatography
Topic overviewMulti-Step Synthesis RoutesGreen Chemistry Principles in Synthesis DesignPrinciples of NMR and the Delta ScaleCarbon-13 NMR InterpretationProton NMR Chemical Shift and IntegrationSpin-Spin Splitting and the n+1 RuleTMS and Deuterated SolventsThin-Layer Chromatography and Rf ValuesColumn and Gas Chromatography, and GC-MS
Periodicity and Group Chemistry
Test for Sulfate Ions
- 3 things to know
- Papers 1 and 3
Overview
Acidified barium chloride, the white precipitate, and why the acid is added first.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Why is sulfuric acid not used to acidify the barium chloride solution in the sulfate ion test?
Key term
How can acidified barium chloride solution be used to distinguish magnesium sulfate solution from magnesium chloride solution?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Why is sulfuric acid not used to acidify the barium chloride solution in the sulfate ion test?
Model answer
Sulfuric acid contains sulfate ions, which would form a white barium sulfate precipitate and give a false positive result
- 2
How can acidified barium chloride solution be used to distinguish magnesium sulfate solution from magnesium chloride solution?
Model answer
Magnesium sulfate solution gives a white precipitate of barium sulfate, whereas magnesium chloride solution gives no precipitate
- 3
What acid is used to acidify the barium chloride solution in the sulfate ion test?
Model answer
Dilute hydrochloric acid
- 4
Write the full equation for the reaction between barium chloride solution and sodium sulfate solution.
Model answer
BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)
- 5
Write the ionic equation for the reaction that occurs when sulfate ions react with barium chloride solution.
Model answer
Ba²⁺(aq) + SO₄²⁻(aq) → BaSO₄(s)
- 6
Why is barium chloride specifically chosen as the reagent for testing sulfate ions?
Model answer
Barium sulfate is insoluble, so barium ions form a precipitate with sulfate ions that can be observed
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