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Multistep Reaction Energy Profile

▶︎  Watch it animatedinteractive step-through · ~3 min · optional

A multistep reaction energy profile shows one barrier (transition state) per elementary step, with an intermediate sitting in the valley between peaks. The highest barrier marks the slowest, rate-determining step. The overall ΔH is still just the difference between the starting reactants and final products.

UNIT 5 TOPIC 5.10 • MULTISTEP REACTION ENERGY PROFILE MULTISTEP REACTION ENERGY PROFILE potential energy reaction coordinate TS1 TS2 TS3 I1 I2 reactants products largest Ea Peaks = transition states TS sit at the tops of the barriers — points of maximum potential energy. Valleys = intermediates Intermediates (I) sit in energy wells between the steps; real species. Rate-determining step The step with the LARGEST activation- energy barrier is the slowest and sets the overall rate. Here that is step 2 (the climb from I1 up to TS2). CED ANCHOR A reaction mechanism is a sequence of elementary steps. The slowest step — the one with the highest Ea — is rate- determining and controls the rate law. AP Chemistry · Unit 5 · Kinetics
A multistep reaction has one barrier per step. Each peak is a transition state; each valley between peaks is an intermediate. The highest barrier corresponds to the slowest, rate-determining step, and the overall ΔH is still just reactants minus products.
Multi-Barrier Profile · Open the sandbox →

The misconceptions misread the profile's features: confusing intermediates (valleys) with transition states (peaks), mistaking which barrier is rate-determining, or confusing a step's Eₐ with the overall ΔH. Peaks are transition states, valleys are intermediates, and the tallest peak is the bottleneck.

The work

3 ways in · any order
Lesson
Multistep Profiles

A multistep profile has a peak per step and a valley per intermediate, with the tallest barrier rate-determining. The lesson reads its features, then closes with a ten-scenario check.

Skill check · 10 scenarios
Diagnostic
10-item topic check

Ten items spanning the Topic 5.10 misconceptions: multistep-profile features misread (peaks vs valleys), the rate-determining barrier misidentified, and step Eₐ confused with overall ΔH.

Not started · 10 items · ~15 min
Targeted Practice
Drill a single misconception

Pick one of the failure modes you missed and drill it on its own. The round is adaptive: two correct in a row clears the misconception and moves you to the next.

Take the diagnostic to identify your misconceptions