Reaction Order in General Chemistry and SN1 and SN2 Mechanisms in Organic Chemistry.

Present by: Professor Ambrose Okpokpo

Present to: Members of Houston Community College North West Campus Interviewing Committee

Chair of Committee: Dr. Emmanuel Ewane

Interview Presentation Room: Spring Branch Campus Room 517

Date of Presentation: Friday 15th, 2013 Time of Presentation: 1: 35 P.M.

Acknowledgment and thanks

• I extend my greetings and thanks for giving me such a rare opportunity to be interviewed by all the distinguished faculties and committee selected for this occasion by the Houston Community College.

• I am truly grateful to be selected for this interview.

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The Rate Law and Order of Reaction

The rate law expresses the relationship of the rate of a reaction to the rate constant and the concentrations of the reactants raised to some powers.

aA + bB cC + dD

Rate = k [A]x[B]y

Reaction is xth order in A

Reaction is yth order in B

Reaction is (x +y)th order overall

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The Overall Order of a reaction is the sum of the individual orders:

Rate (Ms-1) = k [A][B] 1/2[C]2

Overall order: 1 + ½ + 2 = 3.5 = 7/2

or seven-halves order

note: when the order of a reaction is 1 (first order) exponents is written.

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First-Order Reactions

A product rate = -D[A]

Dtrate = k [A]

k = rate

[A]= 1/s or s-1

M/sM

=

D[A]

Dt= k [A]-

[A] is the concentration of A at any time t[A]0 is the concentration of A at time t=0

[A] = [A]0e−kt ln[A] = ln[A]0 - kt

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Second-Order Reactions

A product rate = -D[A]

Dtrate = k [A]2

k = rate

[A]2= 1/M•s

M/sM2

=D[A]

Dt= k [A]2-

[A] is the concentration of A at any time t[A]0 is the concentration of A at time t=0

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[A]=

1

[A]0

+ kt

t½ = t when [A] = [A]0/2

t½ =1

k[A]0

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Zero-Order Reactions

A productrate = -

D[A]

Dtrate = k [A]0 = k

k = rate

[A]0= M/s

D[A]

Dt= k-

[A] is the concentration of A at any time t[A]0 is the concentration of A at time t = 0

t½ = t when [A] = [A]0/2

t½ =[A]0

2k

[A] = [A]0 - kt

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Orientation factors into the equation and/or reaction

The orientation of a molecule during collision can have a profound effect on whether or not a reaction occurs.

Some collisions do not lead to reaction even if there is sufficient energy.

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SN1 and SN2 Structure-Reactivity-Electrophile

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SN1 and SN2 Structure-Reactivity-Electrophile

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SN1 and SN2 Structure-Reactivity-Electrophile

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SN1 and SN2 Structure-Reactivity-Electrophile

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SN1 and SN2 Structure-Reactivity-Nucleophile

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SN1 and SN2 Structure-Reactivity-Electrophile

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SN1 and SN2 Structure-Reactivity-Nucleophile

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SN1 and SN2 Structure-Reactivity-Nucleophile

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SN1 and SN2 Structure-Reactivity-Nucleophile

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SN1 and SN2 Structure-Reactivity-Nucleophile

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SN1 and SN2 Structure-Reactivity-Nucleophile