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 compoundsNaming 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 decimetre
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 phenolphthaleinInvestigating pH change when neutralising an acidBases 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 electrodesElectrolysis of copper sulfate solutionInvestigating the electrolysis of copper sulfate
Extracting Metals and Equilibria
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
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
Measuring rate and interpreting rate graphs
- 3 things to know
- Paper 4
Overview
Methods 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.
What you need to know
Answer each one before you reveal it.
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Key term
Suggest a method for following the rate of a reaction in which a coloured solution slowly fades.
Key term
A reaction slowly produces a precipitate. Suggest how its rate could be measured.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Suggest how the rate of a reaction that gives off a gas could be followed without collecting that gas.
Model answer
The reaction vessel can be stood on a balance and the fall in mass recorded at regular intervals.
- 2
Suggest a method for following the rate of a reaction in which a coloured solution slowly fades.
Model answer
A colorimeter can be used to measure how the intensity of the colour falls with time.
- 3
A reaction slowly produces a precipitate. Suggest how its rate could be measured.
Model answer
The time taken for the mixture to become cloudy enough to hide a mark placed beneath it can be recorded.
- 4
Magnesium ribbon reacts with dilute sulfuric acid. Suggest a suitable method for measuring the rate of this reaction.
Model answer
The hydrogen given off can be collected in a gas syringe and its volume recorded every few seconds.
- 5
Suggest how the rate of a reaction between an acid and an alkali could be followed.
Model answer
A pH probe can be used to record how the pH of the mixture changes with time.
- 6
Why must timing begin at the instant the reactants are mixed?
Model answer
Reactions are fastest at the very start, so a delay means the early, fastest part of the reaction is not recorded.
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