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Reaction Rates

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A reaction rate measures how fast a concentration changes with time — reactants disappear and products appear. The instantaneous rate is the slope of the concentration-time curve at a single instant, and it usually changes as the reaction proceeds. The rates of different species are linked by the reaction's stoichiometry.

UNIT 5 TOPIC 5.1 • REACTION RATES RATE BASICS concentration time [A] decreases [B] increases average rate = secant slope instantaneous rate = tangent slope RATE — STOICHIOMETRIC DEFINITION For aA → bB (reactants → products) rate = − 1 a · Δ[A] Δt = + 1 b · Δ[B] Δt reactant [A] ↓ sign flips → rate stays positive product [B] ↑ AVERAGE RATE slope of the secant line between TWO points on the curve over an interval Δt INSTANTANEOUS slope of the tangent line at ONE point on the curve rate at that instant WHAT CHANGES THE RATE Concentration Temperature Surface area Catalyst CED ANCHOR Rate is the slope of a concentration–time graph. It is always reported as a positive quantity. AP Chemistry · Unit 5 · Kinetics
Reaction rate is how fast a concentration changes with time. Reactants fall and products rise; the instantaneous rate is the slope of the curve at a point, and the rates of different species are tied together by the reaction's stoichiometry.
Rate Tachometer · Open the sandbox →

The mistakes here treat rate as one fixed number, read an average (secant) slope as if it were the instantaneous rate, or forget that stoichiometry ties the species' rates together. Rate is a changing slope, and the coefficients relate how fast each species changes.

The work

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Lesson
Reaction Rates ›

Reaction rate is a changing slope on a concentration-time graph, with species rates tied by stoichiometry. The lesson reads instantaneous versus average rates, then closes with a ten-scenario check.

Skill check · 10 scenarios
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Diagnostic
10-item topic check ›

Ten items spanning the Topic 5.1 misconceptions: rate treated as one fixed value, a secant read as the instantaneous rate, and species rates not related by stoichiometry.

Not started · 10 items · ~15 min
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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.

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