At the pH of most bodily fluids, which functional group will lose a proton and which functional group will accept a proton?

Question

A.  sulfhydryl; carbonyl
B.  Hydroxyl; amino
C.  amino; carboxyl
D.  carboxyl; amino
E.  carbonyl; Hydroxyl

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
· What key words does the question contain and what do they mean?

Gather Content
· What do you know about functional groups? How does it relate to the question?

Consider Possibilities  
· What other information is related to the question? Which information is most useful?

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

D.  carboxyl; amino

Clarify Question
· What is the key concept addressed by the question?
        o The question asks about functional groups that are acids and bases.
· What type of thinking is required?
        o You are being asked to apply your knowledge of functional groups that are acids and bases to predict which would gain or lose a proton at a neutral pH.
· What key words does the question contain and what do they mean?
        o Functional group – a chemical group with specific properties.
        o Proton – an H+ ion that is lost by acids and gained by bases at neutral pH.

Gather Content
· What do you know about functional groups? How does it relate to the question?
        o Functional groups have specific activities based on their chemical structure. They can be polar or non-polar, some can behave as acids or bases.

Consider Possibilities  
· What other information is related to the question? Which information is most useful?
        o Sulfhydryl groups are –SH, these are polar but don’t readily behave as acids.
        o Hydroxyl groups are –OH, these are polar but don’t behave as acids.
        o Carbonyl groups are –CH=O and do not behave as acids.

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Carboxyl groups are –CO2H and the proton (H+) can be lost as an acid forming –CO2-.
        o Amino groups are –NH2 and can gain a proton as a base forming –NH3+.

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o This question asked you to apply the structure of functional groups to predict if they will form an acid or base. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you remember the structures of each of the functional groups? Did you know which would behave as an acid or a base?