Key term
Edexcel GCSE Combined Science Chemistry 1SC0
Key Concepts in Chemistry
Topic overviewFormulae, word equations and balanced equationsHazard symbols and assessing riskThe changing model of the atomProtons, neutrons and electronsThe nucleus, mass number and atomic massElements and isotopesCalculating particle numbers and relative atomic massMendeleev's periodic tableHow the modern periodic table is arrangedElectronic configuration and the periodic tableHow ionic bonds formIons in ionic compoundsFormulae of ionic compounds and ionic equationsNaming compounds and the ionic latticeCovalent bonds and moleculesDot and cross diagrams for simple moleculesClassifying substances and the properties of ionic compoundsProperties of simple molecular substances, and forms of carbonGraphite and diamondFullerenes and graphenePolymers and models of bondingThe properties of metalsRelative formula mass and percentage compositionEmpirical and molecular formulaeConservation of mass in closed and open systemsReacting masses from balanced equationsConcentration in grams per cubic decimetreMoles and the Avogadro constantLimiting reactants and stoichiometry
States of Matter and Mixtures
Topic overviewThe three states of matter and changes of stateEnergy changes during changes of state, and predicting statePure substances and melting point dataChoosing a separation techniqueSeparating a mixture in practicePaper chromatography and interpreting a chromatogramInvestigating inks by distillation and chromatographyMaking water potable
Chemical Changes
Topic overviewAcids, alkalis and the pH scaleIndicators: litmus, methyl orange and phenolphthaleinHydrogen ion concentration and the pH scaleInvestigating pH change when neutralising an acidDilute and concentrated, weak and strong acidsBases and alkalisReactions of acids, and testing for hydrogen and carbon dioxideNeutralisation and its ionic equationPreparing soluble salts from insoluble and soluble reactantsPreparing pure, dry copper sulfate crystalsCarrying out an acid-alkali titrationSolubility rulesPredicting precipitates and preparing an insoluble saltElectrolytes and what electrolysis isMovement of ions and predicting the products of molten electrolysisElectrolysis with inert electrodesWriting half equationsOxidation and reduction at the electrodesElectrolysis of copper sulfate solutionInvestigating the electrolysis of copper sulfate
Extracting Metals and Equilibria
Topic overviewInvestigating the reactivity of metalsDisplacement reactions as redox reactionsThe reactivity seriesOres, oxidation and reductionChoosing a method to extract a metalBiological methods of metal extractionCorrosion resistance and recycling metalsLife cycle assessmentReversible reactions and dynamic equilibriumThe Haber process and its conditionsChanging the position of an equilibrium
Groups in the Periodic Table
Topic overviewThe groups of the periodic table, and the alkali metalsReactions of the alkali metals with waterThe pattern in alkali metal reactivity and why it happensPhysical properties of the halogensThe test for chlorine, and halogens reacting with metalsHydrogen halides, and explaining halogen reactivityDisplacement reactions of the halogensGroup 0: the noble gases
Rates of Reaction and Energy Changes
Topic overviewInvestigating the rate of a reactionMeasuring rate and interpreting rate graphsCollision theory and factors affecting rateCatalysts and enzymesExothermic and endothermic changesBond breaking, bond making and the overall energy changeBond energies, activation energy and reaction profiles
Fuels and Earth Science
Topic overviewHydrocarbons and crude oilFractional distillation and the fractionsProperties of the fractions and homologous seriesComplete and incomplete combustionCarbon monoxide and sootPollutants and acid rainHydrogen and fossil fuels comparedCracking and why it is necessaryThe Earth's early atmosphereHow the oceans formed and how oxygen appearedThe test for oxygen and the greenhouse gasesToday's atmosphere and evidence for climate change
Rates of Reaction and Energy Changes
- 7 subtopics
- 21 things to know
- Paper 4
What Rates of Reaction and Energy Changes covers
Rates of Reaction and Energy Changes is examined in Paper 4, Chemistry 2. It covers investigating the rate of a reaction, measuring rate and interpreting rate graphs, collision theory and factors affecting rate, catalysts and enzymes, exothermic and endothermic changes, bond breaking, bond making and the overall energy change and bond energies, activation energy and reaction profiles.
Where it is assessed
Paper 4
Chemistry 2: Chemistry in Combined Science: 1 hour 10 minutes, 60 marks, 16.67% of the qualification.
Check the Pearson Edexcel specification ↗The 7 subtopics
Each one has its own page.
- Investigating the rate of a reactionFollowing marble chips and acid by gas volume or loss of mass, the variables and errors, and timing the disappearing cross when sodium thiosulfate reacts with hydrochloric acid.Open →
- Measuring rate and interpreting rate graphsMethods for following a reaction by gas, colour, precipitate, mass or pH, why timing starts at mixing, reading rate from the gradient of a graph, and calculating mean rates.Open →
- Collision theory and factors affecting rateThe conditions for a successful collision, collision frequency and energy, how temperature, concentration, surface area and pressure affect rate, why reactions slow as reactants are used up, and calculating surface area to volume ratios.Open →
- Catalysts and enzymesWhat a catalyst is and why it is not used up and changes neither the products nor the yield, why industry uses catalysts, how a lower activation energy pathway speeds a reaction, and enzymes in fermentation and their damage at high temperatures.Open →
- Exothermic and endothermic changesHeat energy changes when salts dissolve and in neutralisation, displacement and precipitation, measuring temperature changes in an insulated cup, exothermic and endothermic changes with everyday examples, and how the energy stored in products compares with reactants.Open →
- Bond breaking, bond making and the overall energy changeWhy breaking bonds is endothermic and making them exothermic, which bonds break and form in a reaction, the conditions for an overall exothermic or endothermic change, and the sign of the energy change.Open →
- Bond energies, activation energy and reaction profilesWorking out the overall energy change from bond energies for HCl, HBr and NO, what activation energy is and why a spark is needed, and reading reaction profiles including a catalysed route.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
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How is the end point of the sodium thiosulfate and hydrochloric acid reaction judged, and why is that judgement a source of error?
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What is activation energy, and how does it explain a spark igniting methane, the effect of heating, and fast reactions at room temperature?
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Explain in terms of collisions how pressure, powdering a solid and cooling affect rate, and why pressure does not affect solutions.
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Suggest how the rate of a reaction that gives off a gas could be followed without collecting that gas.
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Define a catalyst.
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Name four kinds of change in solution that are accompanied by a heat energy change.
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Explain why energy has to be supplied to break a chemical bond.
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Which two substances are reacted together in the investigation that follows a reaction rate by collecting a gas?
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Suggest a method for following the rate of a reaction in which a coloured solution slowly fades.
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Explain why a small quantity of a catalyst can be used over and over again.
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How can the heat change of a reaction carried out in solution be followed in the laboratory?
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What happens to energy when new bonds form between atoms?
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State how the overall energy change of a reaction is worked out from bond energies.
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State two pieces of apparatus that can be used to measure the volume of gas released from acid and marble chips.
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A reaction slowly produces a precipitate. Suggest how its rate could be measured.
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State the two conditions that must be met for reactant particles to react.
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Give one economic reason why industry uses catalysts.
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What temperature change is seen when a dilute acid is neutralised by an alkali?
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In any chemical reaction, which bonds are broken and which are made?
Numbers
Breaking the bonds in a reaction takes in 1500 kJ mol⁻¹ and making the new bonds releases 1350 kJ mol⁻¹. Calculate the overall energy change.
Take Rates of Reaction and Energy Changes further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Exothermic vs Endothermic
Exothermic: change that releases energy to the surroundings, so the temperature rises. Endothermic: change that takes in energy from the surroundings, so the temperature falls.
Bond breaking vs Bond making
Bond breaking: step that takes in energy to pull atoms apart. Bond making: step that releases energy as atoms join together.
Activation energy vs Overall energy change
Activation energy: minimum amount of energy colliding particles need before they can react. Overall energy change: difference between the amount taken in breaking bonds and released making bonds.
Questions from this topic
Each one with the model answer underneath.
- 1
Which two substances are reacted together in the investigation that follows a reaction rate by collecting a gas?
Model answer
Dilute hydrochloric acid is reacted with marble chips, which are calcium carbonate.
- 2
Name the gas given off when hydrochloric acid reacts with marble chips.
Model answer
Carbon dioxide.
- 3
State two pieces of apparatus that can be used to measure the volume of gas released from acid and marble chips.
Model answer
A gas syringe, or an inverted measuring cylinder filled with water over a trough.
- 4
Apart from collecting the gas, how else can the progress of the marble chip and acid reaction be followed?
Model answer
The flask can stand on a balance and the loss in mass be recorded at regular time intervals.
- 5
When the effect of chip size is investigated with acid and marble, which variable is changed and which must be held constant?
Model answer
The size of the marble chips is changed, while the concentration and volume of acid, the mass of marble and the temperature are kept the same.
- 6
Why are readings of gas volume taken every few seconds rather than only at the end of the reaction?
Model answer
Regular readings show how the rate changes as the reaction proceeds, not just the total amount of gas made.
What is inside Levo
Six ways to work the same material.
Rates of Reaction and Energy Changes revision questions
- What does Rates of Reaction and Energy Changes cover in Edexcel GCSE Combined Science Chemistry?
- 7 subtopics: investigating the rate of a reaction, measuring rate and interpreting rate graphs, collision theory and factors affecting rate, catalysts and enzymes, exothermic and endothermic changes, bond breaking, bond making and the overall energy change and bond energies, activation energy and reaction profiles. Each one has its own page with questions and model answers.
- How is Rates of Reaction and Energy Changes organised?
- By the Edexcel 1SC0 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Rates of Reaction and Energy Changes, 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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