Chemistry 211
Fall 2012
Equilibrium Controlled Reactions:
Acid Base Reactions & Energy Relationships - 4
Table B
Conjugate Acid
CH2: CH3
CH4
NH -
~35
NH
:
CH3
CH3
C
CH3
CH3
20
C
O
A. Exploration:
1. Compare the structures below and determine the variables among the structures.
CH3
: :
:
NH2
OH
10
:O
:
CH3 C
H
16
15.7
O:
-
: :
C CH2
: OH
O:
H
: :
: O:
:O :
:O
:
~27
NH
: :
: :
:
NH2
-
H2O
16
:O
:
NH2
O
-
O:
CH3 C
:
:
:
: :
:
:O
:
CH3 C
~36
CH2
CH3
~37
CH3
OH
: :
: :
:
NH2 -
NH3
~40
CH3
pKa
: :
CH3
NH2
: :
:
CH3
Conjugate Base
~42
:
CH3
Conjugate Acid
: :
CH3
pKa
: :
CH3
Conjugate Base
4.8
Acid-Base Rxns & Energy Relationships-4
2
2. Use the data in Table B to list the compounds in 1. in the order of decreasing acidity and provide a warrant citing specific data in Table B
that support your claim. (As usual, more data supporting a warrant makes the claim stronger.)
Most Acidic
Middle
Least acidic
Warrant:
3. Which of the following ions has the lowest energy? Which has the highest energy? Provide a warrant citing specific data in Table B that
support your claims. (As usual, more data supporting a warrant makes the claim stronger.)
O
Lowest Energy
Warrant:
NH
C
CH2
:
O:
C
: :
-
: :
C
O
O
Highest Energy
Acid-Base Rxns & Energy Relationships-4
3
B. Using The Data in Table B, our General Principles and Relative Effect assumption, suggest theoretical backing to explain the effects observed
above in terms of electron nuclear attraction and/or electron-electron repulsion.
Acid-Base Rxns & Energy Relationships-4
4
C. In Class Applications:
1. Using the theoretical backing developed in Part B, select the most acidic proton(s) in the following compound. Then provide a warrant
describing the process and logic that led from the theory to your claim.
H H
H
H
C C H
H
C
H N C
O
C
C
H
H
H
H H
H
2. Use the theoretical backing in this activity to predict whether the equilibrium constant for the following reaction should be > or < 1.
Provide a warrant describing the process and logic that led from the theory to your claim.
O +
NH2
:
NH
: :
H +
: :
O
:
:
:
Acid-Base Rxns & Energy Relationships-4
5
Reflector’s Report Discussion:
Identify the most important concepts you learned from this activity:
What questions remain?
Strategy Analyst’s Report Discussion:
A. Exploration:
What role did question 1 play in the exploration of Table B in question 2?
What Principle or Assumption that wasn’t necessary for question 2 was required to answer question 3?
B. Theoretical Backing:
What fundamental aspect of the variable identified in question A. 1. was the key to providing the backing needed in B.? How was it used?