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Rate equations (A-level only) key terms
Use these key terms for Rate equations (A-level only) in AQA Chemistry 7405. The page is built from approved learning objectives for this topic and links back to the wider unit, topic hub, and related revision assets.
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key terms
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Rate equations (A-level only)
Key terms
initial rate data
The rate of reaction measured at the very beginning of the reaction, providing insight into the reaction's order.
order of reaction
A numerical value that indicates the power to which the concentration of a reactant is raised in the rate equation, reflecting its effect on the reaction rate.
rate equation
An expression that relates the rate of a reaction to the concentration of reactants, each raised to a power corresponding to their order in the reaction.
order of reaction
The power to which the concentration of a reactant is raised in the rate equation, indicating the relationship between concentration and reaction rate.
rate constant
A proportionality constant in the rate equation that relates the rate of a reaction to the concentrations of reactants.
units of rate constant
The units of the rate constant depend on the overall order of the reaction; for a first-order reaction, the unit is s⁻¹, while for a second-order reaction, it is mol⁻¹ dm³ s⁻¹.
half-life
The time required for the concentration of a reactant to decrease to half of its initial value in a first-order reaction.
first-order reaction
A reaction whose rate is directly proportional to the concentration of one reactant.
concentration-time graph
A graph that plots the concentration of a reactant or product against time, showing how concentration changes during a reaction.
reaction order
The power to which the concentration of a reactant is raised in the rate equation, indicating how the rate of reaction is affected by changes in concentration.
rate-determining step
The slowest step in a reaction mechanism that determines the overall reaction rate.
mechanism
A detailed description of the steps involved in a chemical reaction, including the sequence of elementary reactions.
rate equation
An expression that relates the rate of a chemical reaction to the concentration of reactants, typically in the form rate = k[A]^m[B]^n, where k is the rate constant, and m and n are the orders of reaction.
mechanism
The step-by-step sequence of elementary reactions by which overall chemical change occurs, including the identification of the rate-determining step.
rate equation
An expression that relates the rate of a chemical reaction to the concentration of its reactants, each raised to a power known as the order.
rate-determining step
The slowest step in a reaction mechanism that determines the overall rate of the reaction.
overall equation
The overall equation represents the complete balanced chemical reaction, showing all reactants and products.
rate-determining step
The rate-determining step is the slowest step in a reaction mechanism that controls the overall reaction rate.
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