Concentration
Concentration workflows across stoichiometry, titration, and collision-theory reasoning.
This route helps when you keep missing the same type of question across different topics. Use it to combine lesson notes with linked practice and tools in one place.
Notes and Hubs in This Route
- Introduction to Acids
Acids: aqueous hydrogen ions, complete versus partial ionisation, and the distinction between acid strength and concentration.
- Catalysts and Enzymes
Explain how catalysts lower activation energy, distinguish elements from compound catalysts, and understand enzymes as biological catalysts.
- Collision Theory
Collision theory: explain effective collisions, activation energy and how particle behaviour changes reaction rate.
- Diffusion
Diffusion: net movement from high to low concentration, particle explanation, and factors affecting speed (temperature, state, molecular mass).
- Factors Affecting Rate of Reaction
Explain concentration, gas compression, solid particle size and temperature using collisions; compare rates with fair tests and graphs.
- Introduction to Bases
Bases and alkalis: definitions, aqueous hydroxide ions, neutralisation and the ammonium-ion reaction.
- Limiting reactants and excess left over
Limiting reactant: identify what runs out first using moles and the balanced equation, then calculate theoretical yield and excess left.
- Manufacturing Ammonia (Haber Process)
Haber process: feedstocks, reversible equation, ammonia separation, gas recycling and interpretation of supplied industrial data.
- Moles, molar mass and particle counts
Use the mole to connect mass and particle counts. Choose the correct entity and molar mass, keep units consistent and round the final answer.
- pH Scale & Indicators
pH scale & indicators: acidic/neutral/alkaline ranges, key colour changes (litmus/universal indicator), and how to answer exam-style questions.
- Rate of Reactions
Rate of Reactions hub for G3 Pure / O-Level Chemistry K324 / 6092: measurement, graphs, collision theory, rate factors, catalysts and investigations.
- Reading Reaction-Rate Graphs
Read gas-volume and mass-loss graphs, calculate average rates over intervals and estimate instantaneous rates using tangents.
- Solution concentration and titration calculations
Use mass and molar concentration, conserve solute amount during dilution, and calculate an unknown concentration from a titration and its balanced equation.
- Stoichiometry & The Mole Concept
Chemistry stoichiometry hub: formulas, balanced equations, mole calculations, concentration, limiting reagent, and yield/purity. Practise the topic with its check.
- Measuring Reaction Rate
Choose a fixed end-point, gas-syringe or mass-loss method, plan a fair rate comparison and recognise measurement limitations.
- Speed of Reaction
Rate of reaction: define change per unit time, choose a measurable quantity, calculate rates with units and interpret reaction graphs.
- Activation Energy and Boltzmann Distribution (A Level)
Use collision theory to explain temperature effects on rate via the Boltzmann distribution and the fraction of particles with E ≥ Ea.
- Reaction Kinetics (A Level)
A Level reaction kinetics notes: rate laws and orders, initial rates, concentration–time graphs and half-life, mechanisms/RDS, and catalysis.
- Catalysis and Enzymes (A Level)
Compare homogeneous vs heterogeneous catalysis, explain how catalysts lower Ea, and describe enzymes as specific catalysts with temperature/pH effects.
- Concentration–Time Graphs and Half-life (A Level)
Recognise 0th and 1st order behaviour from concentration–time and rate plots, use half-life to test reaction order, and extract k correctly.
- Empirical and Molecular Formula (A Level)
Use the exam-proof workflow to find empirical and molecular formulae from composition data, including hydrates and combustion-style traps.
- Gas Calculations (pV = nRT) (A Level)
Use pV = nRT safely: consistent units, correct R, Pa/kPa and cm³↔dm³ conversions, and gas stoichiometry traps that lose marks.
- Initial Rates Method (A Level)
Deduce reaction orders from initial-rate data and build the rate equation using comparisons, including the common table-reading and rounding traps.
- Mechanisms and Rate-determining Step (A Level)
Link mechanisms to rate equations using the slow step (RDS), and perform the ‘consistency check’ between mechanism and observed rate law.
- Mole and Avogadro Constant (A Level)
Learn the mole as a counting unit: Avogadro constant (NA), particles vs moles, and the core equations you reuse everywhere.
- Rate Equations, Orders, Rate Constant (A Level)
Use rate equations to connect rate to concentration, deduce orders, and handle rate constant k units with methodical comparisons and checks.
- Reacting Masses and Limiting Reagent (A Level)
Solve reacting-mass questions reliably: find the limiting reagent, calculate theoretical yield, handle leftovers, and avoid ratio-table mistakes.
- Solution Concentration and Dilution (A Level)
Use c = n/V and c1V1 = c2V2 safely with correct units (dm³ vs cm³), and avoid the most common dilution and mixing mistakes.
- Stoichiometry (A Level)
A Level stoichiometry notes: moles, formulas, limiting reagent, solutions and titrations, and gas calculations (pV = nRT) with strict units.
- Titration Calculations (A Level)
A Level titration arithmetic: a repeatable method from balanced equation to moles to concentration, with correct units and ratios.
- The Chemistry of Chocolate: Flavour, Texture, and Tempering
Chocolate is engineered from cocoa beans using fermentation, roasting, and careful crystal control. Here’s the chemistry behind flavour and snap.
- The Chemistry of Cocktails: Layers, Emulsions, and Aroma
Great cocktails rely on solubility, density, temperature, and volatile aromas. Here’s the chemistry behind shaking, stirring, and layering.
- The Chemistry of Sourdough: Fermentation, Flavour, and Texture
Sourdough is controlled fermentation. Learn what the starter microbes do, how acids change flavour and texture, and why time and temperature matter.