Kinetics Study Guide - Moore Public Schools

Supplemental Study Guide
Chemical Kinetics and Electrochemistry
Chemical kinetics – the study of the reaction rates in a chemical reaction or group of
chemical reactions – determines the rate of a chemical reaction
Electrochemistry – the study of the chemical reactions that take place in the presence of
an electrode and an electrolyte
Electrode – a piece of metal (conductor) that comes in contact with a nonmetallic, ionic
conductor (electrolyte)
Electrolyte – a solution that contains flowing ions
Redox reactions – short for oxidation –reduction reactions - result in a change in
oxidation states
Oxidation – occurs when a substance loses electrons. We say the substance has been
Reduction – a substance that gains electrons. We say the substance has been reduced
Oxidation state – number of electrons available to be accepted or donated – changes as
the result of electron transfer (donates/oxidized, accepts/reduced)
Rate law – an equation that shows how the rate of reaction depends on the concentration
of reactants.
Reaction rates are influenced by pressure, concentration of the reactants, reaction
complexity, catalysts, physical state, temperature, reaction rte order, and surface area
Collision theory of reaction rates – in order for a chemical reaction to proceed, molecules
must collide with one another – as the concentration of the reactants increases, the
frequency of the collisions increases
Catalyst - a substance that accelerates the rate of a chemical reaction but remains
unchanged afterwards
Activation energy – the minimum amount of energy required to initiate a chemical
Chemical equilibrium – a property that determines how far a reaction will proceed – the
concentrations of the products and reactants no longer change
Electrochemistry – chemical reactions are caused by an electrical current or produce an
electrical current
Electrochemical cell – a device capable of producing electric current from energy
released by a redox reaction - differing electrode potentials help drive the reactions
Galvanic cells – the anode loses electrons (corrodes) through the electrolyte to the
cathode – oxidation takes place at the anode – reduction takes place at the cathode –
electrons flow from the anode to the cathode in a solution (electrolyte) – the metals react
in the form of half reactions resulting in a difference of electrons which produces an
electric current
Law of mass action – applies to single-step reactions – the speed of a chemical reaction is
proportional to the amount of the reacting substances
Single step reaction – proceed from start to finish without an intermediate step (another
product that is formed on the way – treated as an additional reaction)
Reaction mechanism – a step-by-step reaction pathway
Arrhenius equation – expresses temperature dependency of a chemical reaction rate
K is the reaction rate constant.
Ea is the activation energy, measured in joules/mole.
R is the gas constant (0.08205746 Latm K-1 mol-1).
T is the temperature, measured in kelvins (K).
A is the frequency factor (specific to reaction).
Chemical Equilibrium
Zero order rate reaction –a valid rate law - the reaction rate will not increase by
increasing the concentration of the reactants – does not depend on the concentration of
the reactants
where r is the reaction rate,
k is the reaction rate coefficient, expressed as concentration/time
First order rate reaction – a valid rate law - depends on the concentration of only one
r =k[X]
where k is the first order rate constant, expressed as units of time-1.
[X] is the concentration of one reactant (first order), expressed as mol/L
Second order rate laws – are dependent on the concentrations of one second-order
reactant or two first order reactants
r = k[X][Y]
R = k[X]x[Y]y
Law of conservation of energy – energy can neither be created or destroyed