Chemical Kinetics Two Types of Rate Laws 1.Differential - Data table contains RATE AND CONCENTRATION DATA. Uses “table logic” or algebra to find the order of reaction and rate law 2.Integrated - Data table contains TIME AND CONCENTRATION DATA. Uses graphical methods to determine the order of the given reactant. K=slope of best fit line found through linear regressions
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Chemical Kinetics Two Types of Rate Laws 1.Differential- Data table contains RATE AND CONCENTRATION DATA. Uses “table logic” or algebra to find the order.
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ChemicalKinetics
Two Types of Rate Laws
1. Differential- Data table contains RATE AND CONCENTRATION DATA. Uses “table logic” or algebra to find the order of reaction and rate law
2. Integrated- Data table contains TIME AND CONCENTRATION DATA. Uses graphical methods to determine the order of the given reactant. K=slope of best fit line found through linear regressions
ChemicalKinetics
Integrated Rate Law
• Can be used when we want to know how long a reaction has to proceed to reach a predetermined concentration of of some reagent
ChemicalKinetics
Graphing Integrated Rate Law
• Time is always on x axis
• Plot concentration on y axis of 1st graph
• Plot ln [A] on the y axis of the second graph
• Plot 1/[A] on the y axis of third graph
• Your are in search of a linear graph
ChemicalKinetics
Results of linear graph• Zero order: time vs concentration= line
y= mx+ b
[A]= -kt + [A0 ]
A- reactant A,
A0 - initial concentration of A at t=0
l slope l= k, since k cannot be negative, and k will have a negative slope
Rate law will be rate=k[A]0
ChemicalKinetics
Results of linear graph• First order: time vs ln [ ]= line
y= mx+ b
ln [A]= -kt + ln [A0 ]
A- reactant A,
A0 - initial concentration of A at t=0
l slope l= k, since k cannot be negative, and k will have a negative slope
Rate law will be rate=k[A]1
ChemicalKinetics
Results of linear graph• second order: time vs 1/ [ ]= line
y= mx+ b
1/[A]= kt + 1/ [A0 ]
A- reactant A,
A0 - initial concentration of A at t=0
k=slope
Rate law will be rate=k[A]1
ChemicalKinetics
First-Order Processes
Consider the process in which methyl isonitrile is converted to acetonitrile.
Here the rate only depends on the concentration of _______________
and therefore the rate equation only contains this reactant
The rate equation is, ______________ in the rate determining step is 1.
Note: R and Q are not reactants or products, but are rather they are called ________________________, produced in one step, but then are used up in a subsequent step.
Here the slow step contains Q and B, and _____is an intermediate
Can intermediates be featured the rate equation? _____________
Since the formation of Q is dependent on A, Q can be replaced by A in the rate equation. Therefore the rate equation is given as_________________ The orders w.r.t A and B are________________________________
since the stoichiometric coefficient of B in the rate determining step is 1, and the stoichiometric coefficient of A (which Q depends upon) is also 1.
• If the dotted line represents the activation energy, then as the temperature increases, so does the fraction of molecules that can overcome the activation-energy barrier.