IB Chemistry Topic 6 Chemical kinetics
6.1 Collision theory and rates of reaction SL
• Species react as a result of collisions of sufficient energy and proper orientation.
• The rate of reaction is expressed as the change in concentration of a particular reactant/product per unit time.
• Concentration changes in a reaction can be followed indirectly by monitoring changes in mass, volume and colour.
• Activation energy (Ea) is the minimum energy that colliding molecules need in order to have successful collisions leading to a reaction.
• By decreasing Ea, a catalyst increases the rate of a chemical reaction, without itself being permanently chemically changed.
• Description of the kinetic theory in terms of the movement of particles whose average kinetic energy is proportional to temperature in Kelvin.
• Analysis of graphical and numerical data from rate experiments.
• Explanation of the effects of temperature, pressure/concentration and particle size on rate of reaction.
• Construction of Maxwell–Boltzmann energy distribution curves to account for the probability of successful collisions and factors affecting these, including the effect of a catalyst.
• Investigation of rates of reaction experimentally and evaluation of the results.
• Sketching and explanation of energy profiles with and without catalysts.
• The rate of reaction is expressed as the change in concentration of a particular reactant/product per unit time.
• Concentration changes in a reaction can be followed indirectly by monitoring changes in mass, volume and colour.
• Activation energy (Ea) is the minimum energy that colliding molecules need in order to have successful collisions leading to a reaction.
• By decreasing Ea, a catalyst increases the rate of a chemical reaction, without itself being permanently chemically changed.
• Description of the kinetic theory in terms of the movement of particles whose average kinetic energy is proportional to temperature in Kelvin.
• Analysis of graphical and numerical data from rate experiments.
• Explanation of the effects of temperature, pressure/concentration and particle size on rate of reaction.
• Construction of Maxwell–Boltzmann energy distribution curves to account for the probability of successful collisions and factors affecting these, including the effect of a catalyst.
• Investigation of rates of reaction experimentally and evaluation of the results.
• Sketching and explanation of energy profiles with and without catalysts.

Using the collision theory to understanding the kinetics of reaction rates
0:00 Collision theory Spartan version 1:01 Collision theory IB version 1:50 Enthalpy diagram activation energy 2:33 Reaction rates: Collision rate vs activation energy 2:55 Reaction rates: Concentration 3:37 Reaction rates: Surface area 4:25 Reaction rates: Temperature 5:05 MaxwellBoltzmann curve with temperature 6:10 Reaction rates: Catalysts 6:36 MaxwellBoltzmann curve with catalysts 7:04 Enthalpy diagram with catalysts 7:17 Rate of reaction formula 7:34 Preparing for rates of reaction experiments 8:19 Rate of reaction experiments: Gas collection 9:08 Rate of reaction experiments: Change in mass 9:32 Rate of reaction experiments: Spectrophotometry 9:54 Rate of reaction experiments: pH or conductivity 10:41 Rate of reaction experiments: Clock reactions 10:52 Rate of reaction graph and calculations 
PhET simulation: Reactions & Rates
CONCEPT VIDEOS:

EXPERIMENTAL VIDEOS:

EXAM PAST PAPER QUESTION VIDEOS SL:


End of Unit Quiz Topic 6 SL:
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16.1 Rate expression and reaction mechanism HL
• Reactions may occur by more than one step and the slowest step determines the rate of reaction (rate determining step/RDS).
• The molecularity of an elementary step is the number of reactant particles taking part in that step.
• The order of a reaction can be either integer or fractional in nature. The order of a reaction can describe, with respect to a reactant, the number of particles taking part in the ratedetermining step.
• Rate equations can only be determined experimentally.
• The value of the rate constant (k) is affected by temperature and its units are determined from the overall order of the reaction.
• Catalysts alter a reaction mechanism, introducing a step with lower activation energy.
• Deduction of the rate expression for an equation from experimental data and solving problems involving the rate expression.
• Sketching, identifying, and analysing graphical representations for zero, first and second order reactions.
• Evaluation of proposed reaction mechanisms to be consistent with kinetic and stoichiometric data.
• The molecularity of an elementary step is the number of reactant particles taking part in that step.
• The order of a reaction can be either integer or fractional in nature. The order of a reaction can describe, with respect to a reactant, the number of particles taking part in the ratedetermining step.
• Rate equations can only be determined experimentally.
• The value of the rate constant (k) is affected by temperature and its units are determined from the overall order of the reaction.
• Catalysts alter a reaction mechanism, introducing a step with lower activation energy.
• Deduction of the rate expression for an equation from experimental data and solving problems involving the rate expression.
• Sketching, identifying, and analysing graphical representations for zero, first and second order reactions.
• Evaluation of proposed reaction mechanisms to be consistent with kinetic and stoichiometric data.

0:23 The rate equation
0:32 Order of reaction 1:13 Units for the rate constant k 2:26 Graphical determination of rate 2:46 Determining order with concentration vs time graph 3:45 Determining order with rate vs concentration graph 5:04 Rate of reaction calculations 6:12 Reaction mechanisms 8:17 Unimolecular vs bimolecular steps 8:59 Intermediate vs transition states 9:29 Enthalpy diagram: Intermediate vs transition states 10:05 Determining order of reaction from reaction mechanisms 11:26 Practice problems 
16.2 Activation energy HL
• The Arrhenius equation uses the temperature dependence of the rate constant to determine the activation energy.
• A graph of 1/T against ln k is a linear plot with gradient – Ea/R and intercept, lnA.
• The frequency factor (or preexponential factor) (A) takes into account the frequency of collisions with proper orientations.
• Analysing graphical representation of the Arrhenius equation in its linear form lnk = Ea/RT + lnA.
•Using the Arrhenius equation k = Ae^(Ea/RT).
• Describing the relationships between temperature and rate constant; frequency factor and complexity of molecules colliding.
• Determining and evaluating values of activation energy and frequency factors from data.
• A graph of 1/T against ln k is a linear plot with gradient – Ea/R and intercept, lnA.
• The frequency factor (or preexponential factor) (A) takes into account the frequency of collisions with proper orientations.
• Analysing graphical representation of the Arrhenius equation in its linear form lnk = Ea/RT + lnA.
•Using the Arrhenius equation k = Ae^(Ea/RT).
• Describing the relationships between temperature and rate constant; frequency factor and complexity of molecules colliding.
• Determining and evaluating values of activation energy and frequency factors from data.

0:17 Arrhenius equation
1:06 Arrhenius plot 1:40 Determining activation energy Ea 2:09 Practice problems 
EXAM PAST PAPER QUESTION VIDEOS HL:

End of Unit Quiz Topic 6 HL:
When you are confident with all the concepts please try this quiz. These are based of IB Chemistry exam past paper 1 questions. Make sure you get 100%. If you don't please refresh the page and try it again.
