Kinetics II

Question 1

What is the rate equation?

Answer 1

• k[A]^m[B]^n

Question 2

how will a conc-rate graph look for a 0 order reaction?

Answer 2

• Flat line (m of 0)

Question 3

How will a con-rate graph look for a 1st order reaction?

Answer 3

• straight line going through the origin (positive m)

Question 4

How will a con-rate graph look for a 2nd order reaction?

Answer 4

• exponential graph with a positive m

Question 5

What does it tell us if half lives of a conc-time graph are constant?

Answer 5

its 1st order

Question 6

What does it tell us if half lives of a conc-time graph are rapidly increasing (or vary very weirdly?)

Answer 6

its 2nd order

Question 7

What does it tell us if half lives of a conc-time graph are a straight line with a negative m?

Answer 7

it is 0 order

Question 7

what are the units of an overall reaction of 2nd order?

Answer 7

mol^-1dm^3s^-1

Question 7

what are the units of an overall reaction of 1st order?

Answer 7

s^-1

Question 8

what are the units of an overall reaction of 3rd order?

Answer 8

• mol^-2dm^6s^-1

Question 9

give some key points of Sn1 reactions?

Answer 9

• only have 1 molecule or ion in the rate determining step (rate equation)
• tertiary or secondary haloalkanes react through this mechanism

Question 10

Describe Sn1 reactions

Answer 10

• curly arrow from middle of C-X bond to X-
• forms a carbocation with a X-
• OH- ion attacks carbocation (which will be a positive)

Question 10

Describe Sn2 reactions

Answer 10

• forms an intermediate from nucleophillic substitution (kind of like a halogen and OH- competing for the spot)
• HAPPENS IN ONE STEP

Question 10

Give some key points of Sn2 reactions

Answer 10

• only 1 rate determining step
• have 2 molecules or ions in the rate determining step. ( rate equation)

Question 10

Why do tertiary haloalkanes proceed via Sn1 reactions?

Answer 10

• Because there is less space around their alkyl groups (they’re larger) for nucleophiles to attack,