Numbers
AQA AS-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
Chemical Equilibria
Redox and Electrochemistry
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
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
Amount of Substance
- 8 subtopics
- 24 things to know
- Papers 1, 2 and 3
What Amount of Substance covers
Amount of substance is examined on Papers 1, 2 and 3, and is the topic every calculation in the specification leans on. It runs from relative masses and the mole through gas volumes, formulae, yields and titrations.
Where it is assessed
Papers 1, 2 and 3
Physical chemistry drawn on by both written papers.
Check the AQA specification ↗The 8 subtopics
Each one has its own page. AQA AS Chemistry students sit this topic in the first year.
- Relative Atomic and Molecular MassWhat relative atomic and molecular mass mean, and why carbon-12 is the standard.Open →
- The Mole and the Avogadro ConstantThe mole, the Avogadro constant, and converting between mass, moles and particles.Open →
- The Ideal Gas EquationpV = nRT, the units each term must be in, and using it to find moles or molar mass.Open →
- Empirical and Molecular FormulaWorking out empirical formula from composition, and scaling it to the molecular formula.Open →
- Balanced Equations and Reaction CalculationsBalancing equations and using the ratios in them to work out reacting masses.Open →
- Atom Economy and Percentage YieldCalculating both, telling them apart, and why industry cares about each.Open →
- Acid-Base Titrations: Principles, Indicators and ApparatusWhat a titration measures, choosing an indicator, and the apparatus and technique that make the result reliable.Open →
- Acid-Base Titrations: Standard Solutions and CalculationsMaking up a standard solution, and working concentration out from titre using moles = concentration × volume.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
What formula relates the concentration, volume, and number of moles of a solution?
Key term
What is the formula relating moles, concentration and volume?
Numbers
A burette has an uncertainty of ±0.05 cm³ per reading. Calculate the percentage uncertainty in a titre of 25.00 cm³.
Key term
What is relative atomic mass?
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What is the Avogadro constant?
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What does the Avogadro constant represent?
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State the ideal gas equation.
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What does n represent in the ideal gas equation?
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What is the definition of empirical formula?
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What is the definition of molecular formula?
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What must be conserved in a balanced chemical equation?
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What is the formula for calculating atom economy?
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Why is atom economy an important consideration in industrial chemistry?
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What type of reaction is typically involved in an acid-base titration?
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What is the equivalence point in a titration?
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What standard is used as the reference for relative atomic mass?
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To what types of particles can the mole be applied?
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What does R represent in the ideal gas equation?
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How does the molecular formula relate to the empirical formula?
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In terms of atoms, what does balancing a chemical equation ensure?
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What type of reaction has 100% atom economy?
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What is the difference between the equivalence point and the end point of a titration?
Key term
How do you convert volume in cm³ to volume in dm³?
Take Amount of Substance further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Empirical formula vs Molecular formula
Empirical formula: simplest whole-number ratio of atoms of each element. Molecular formula: actual number of atoms of each element in one molecule.
Percentage yield vs Atom economy
Percentage yield: actual product amount divided by theoretical product amount, multiplied by one hundred. Atom economy: desired product formula mass divided by all product formula masses, multiplied by one hundred.
Standard solution vs Stock solution
Standard solution: a solution with an accurately known concentration. Stock solution: a concentrated solution used to prepare more dilute solutions.
Questions from this topic
Each one with the model answer underneath.
- 1
What is relative atomic mass?
Model answer
The weighted mean mass of an atom of an element relative to one-twelfth of the mass of an atom of carbon-12.
- 2
What standard is used as the reference for relative atomic mass?
Model answer
One-twelfth of the mass of an atom of carbon-12.
- 3
Why is carbon-12 used as the standard for relative atomic mass?
Model answer
Carbon-12 is a stable isotope with a precisely defined mass, providing a consistent reference standard.
- 4
What is relative molecular mass?
Model answer
The weighted mean mass of a molecule relative to one-twelfth of the mass of an atom of carbon-12.
- 5
How is relative molecular mass calculated from a molecular formula?
Model answer
By adding together the relative atomic masses of all atoms present in the molecular formula.
- 6
What is relative formula mass?
Model answer
The weighted mean mass of a formula unit relative to one-twelfth of the mass of an atom of carbon-12.
What is inside Levo
Six ways to work the same material.
Amount of Substance revision questions
- Is Amount of Substance examined at AS in AQA Chemistry?
- Yes. It sits in Papers 1, 2 and 3, which you take in the first year, so it is on the AS paper as well as counting towards the full A level.
- What does Amount of Substance cover in AQA AS-Level Chemistry?
- 8 subtopics: relative atomic and molecular mass, the mole and the avogadro constant, the ideal gas equation, empirical and molecular formula, balanced equations and reaction calculations, atom economy and percentage yield, acid-base titrations: principles, indicators and apparatus and acid-base titrations: standard solutions and calculations. Each one has its own page with questions and model answers.
- How is Amount of Substance organised?
- By the AQA 7405 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Amount of Substance, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
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