Chemical reactions are like races, with molecules sprinting to form new compounds. Reaction rates measure this molecular sprint, telling us how quickly reactants transform into products. Understanding rates helps us control reactions and predict their outcomes.
Reaction rates aren't constant - they change as the reaction progresses. We can measure instantaneous rates at specific moments or calculate average rates over time. Stoichiometry plays a crucial role, linking rates of different species in the reaction.
Reaction Rate Concepts and Definitions
Definition of reaction rate
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Top images from around the web for Definition of reaction rate
Chemical Reaction Rates – Atoms First / OpenStax View original
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Chemical Reaction Rates | Chemistry for Majors View original
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The Rate Law: Concentration and Time | Boundless Chemistry View original
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Chemical Reaction Rates – Atoms First / OpenStax View original
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Measure of how fast the concentrations of reactants and products change over time in a chemical reaction
Mathematically expressed as the change in concentration of a reactant or product per unit time
For a reactant A: rate=−ΔtΔ[A]
For a product B: rate=ΔtΔ[B]
Square brackets [] denote concentration, typically measured in molarity (M) or moles per liter (mol/L)
Negative sign for reactants indicates their concentration decreases as the reaction progresses
Reaction rates are always positive values
Units for depend on the reaction order (zeroth, first, second) and are typically or mol/(L·s)
Concept of instantaneous rate
Rate of a reaction at a specific point in time or moment
Determined by calculating the slope of the tangent line to the concentration vs. time curve at that point
Provides a snapshot of the reaction rate at a particular instant
Instantaneous rates change throughout the course of a reaction
Highest at the beginning when reactant concentrations are greatest ()
Decrease as the reaction progresses and reactant concentrations diminish