GCSE›AQA GCSE Chemistry›Mind mapsRates of ReactionAQA GCSE Chemistry: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsRateRate = quantity used or formed ÷ timeUnits: g/s, cm³/s or mol/(dm³·s)Steeper gradient = faster rateMeasuringMass loss for gas-producing reactionsGas volume collected over timeCross experiment: time until the cross disappearsPrecipitate formation shows how fast the solid formsCollision theoryParticles must collide with enough energyMore frequent collisions → faster rateActivation energy is the minimum energy to reactRatesrates of reactiong/scm³/sChanging rateHigher concentration: more particles per volumeHigher surface area: powder beats lumpsHigher temperature: faster and more energetic collisions(HT) More particles exceed activation energyCatalyst lowers activation energy, not used upGraph tangents (HT)Draw a tangent at the point on the curveGradient = change in y ÷ change in xTangent gradient = rate at that momentExam tipsAlways include units in the answerConcentration–time is not the same as rate–time graphConcentration does not change activation energyUse a ruler; extend the tangent across the graph