CCEA A-Level Chemistry 1110
Formulae, Equations and Amounts of Substance
Atomic Structure
Bonding
Intermolecular Forces and Structure
Shapes of Molecules and Ions
Redox
The Halogens
Acid-Base Titrations
Qualitative Tests
Formulae and Amounts of a Substance
Nomenclature and Isomerism in Organic Chemistry
Alkanes
Alkenes
Halogenoalkanes
Alcohols
Infrared Spectroscopy
Energetics
Kinetics
Equilibrium
Group II Elements and Their Compounds
Lattice Enthalpy, Entropy and Free Energy
Rates of Reaction
Equilibrium and Acid-Base Equilibria
Isomerism
Aldehydes and Ketones
Carboxylic Acids
Derivatives of Carboxylic Acids
Aromatic Chemistry
Spectroscopy and Chromatography
Volumetric Analysis
Transition Metals
Electrode Potentials
Amines
Amides and Polymers
Amino Acids and Proteins
Rates of Reaction
Deducing rate equations from initial rate data
- 3 things to know
- Unit A2 1
Overview
Recall questions on why the initial rate is used, reading the order for one reactant from a table when concentration is doubled or trebled, deducing a whole rate equation from two experiments, calculating the rate constant and its units, using the equation to predict a rate, and why only one concentration is changed at a time.
What you need to know
Answer each one before you reveal it.
Describe how the order with respect to one reactant is found from a table of initial rate data.
Doubling the concentration of a reactant doubles the initial rate. State the order with respect to that reactant.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Why is the initial rate used rather than a rate measured later in the reaction?
Model answer
At the very start the concentrations are known exactly and no products have built up, so the measured rate corresponds to the stated concentrations.
- 2
Describe how the order with respect to one reactant is found from a table of initial rate data.
Model answer
Two experiments are compared in which only that reactant's concentration differs, and the factor by which the rate changes gives the order directly.
- 3
Doubling the concentration of a reactant doubles the initial rate. State the order with respect to that reactant.
Model answer
The reaction is first order with respect to that reactant.
- 4
Doubling the concentration of a reactant quadruples the initial rate. State the order with respect to that reactant.
Model answer
The reaction is second order with respect to that reactant.
- 5
Doubling the concentration of a reactant leaves the initial rate unchanged. State the order with respect to that reactant.
Model answer
The reaction is zero order with respect to that reactant.
- 6
In a reaction of A with B, doubling [A] at constant [B] quadruples the rate and doubling [B] at constant [A] doubles the rate. Write the rate equation.
Model answer
The rate equation is rate = k[A]²[B].
Other ways to work this
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