IB›IB Chemistry SL›Mind mapsR2.2 How fast? The rate of chemical changeIB Chemistry SL: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsMeasuring rateChange in concentration per unit timeUnits mol dm⁻³ s⁻¹Follow gas volume, mass loss, colour or conductivityFixed product formed: rate ∝ 1/timeRate is highest at the startCollision theoryCollide with E≥EaE \geq E_aE≥EaCorrect orientation neededMost collisions are unsuccessfulMean kinetic energy ∝ temperature in KFactorsConcentration or pressure: more frequent collisionsBigger surface area: more frequent collisionsTemperature: larger proportion with E≥EaE \geq E_aE≥EaCatalyst: lowers EaE_aEaSolution volume alone: no effectRatehow fast?EaTkBoltzmann curvesNumber of particles against kinetic energyArea under curve = total particlesHigher T: peak lower and to the rightHigher T: much more area beyond EaE_aEaCatalyst: curve same, EaE_aEa moves leftCatalystsAlternative pathway with lower EaE_aEaNot used upΔH unchangedLowers forward and reverse EaE_aEa equallyExam tipsKey reason for temperature: proportion with E≥EaE \geq E_aE≥EaCheck the time unit: min is 60 × sRate in cm³ min⁻¹ is 60 × bigger than cm³ s⁻¹