This Additional Higher Level mini-lesson covers Reactivity 2.2 & 2.3: rate laws and order, the rate constant, the rate-determining step, the Arrhenius equation, and Kc calculations.
Work through each screen, answer the questions as you go (some are wordy, some are calculations) and collect ⭐ stars. Press Start when you're ready.
The rate law is found by experiment, not from the equation:
Order shows how rate responds to concentration: zero order (no effect), first order (∝), second order (∝ square).
Using the initial-rates method: if doubling [A] doubles the rate, it is first order in A; if it quadruples the rate, second order. The rate constant k is then found by substituting one experiment into the rate law.
A reaction proceeds by elementary steps. The rate-determining step (RDS) is the slowest step; only species involved up to and including the RDS appear in the rate law. The molecularity of the RDS matches the orders.
Temperature dependence of k is described by:
Higher temperature (or a catalyst lowering Ea) increases k.
An ICE table (Initial, Change, Equilibrium) tracks concentrations. Use the change (from the stoichiometry and the amount reacted) to find equilibrium concentrations, then substitute into the Kc expression.
Equilibrium position connects to thermodynamics:
Tap a phrase, then the concept it belongs to.
Tap an item on the left, then its match on the right.
Rate law: rate = k[A]ᵐ[B]ⁿ from experiment; overall order = m + n
Mechanism: rate-determining (slowest) step sets the rate law
Arrhenius: k = A e^(−Ea/RT); ln k vs 1/T gives −Ea/R
Kc: from ICE tables; ΔG° = −RT ln K links extent to spontaneity
You've covered Rate laws and equilibrium calculations (AHL) for IB Diploma Chemistry HL. Press Finish to see your score.
You've worked through Rate laws and equilibrium calculations (AHL) for IB Diploma Chemistry HL. 🎉
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