Question 1

Which of the following molecules will not form hydrogen bonds?

Accepted Answer

A)  CH4 
B)  NH3 
C)  H2O 
D)  HF 
A)  CH4 
B)  NH3 
C)  H2O 
D)  HF

Question 2

An ammonia buffer contains NH3:NH4+ in a ratio of 0.4 moles:0.6 moles (pK = 9.75). What will be the pH if you add 0.01 moles of HCl to this buffer?

Accepted Answer

A)  8.98 
B)  9.04 
C)  9.25 
D)  9.46 
E)  9.52 
A)  8.98 
B)  9.04 
C)  9.25 
D)  9.46 
E)  9.52

Question 3

Buffers work to maintain pH because

Accepted Answer

A)  they obey LeChatlier's principle 
B)  weak acids cannot change the pH of a solution 
C)  weak bases added to strong bases neutralize each other 
D)  they destroy the hydrogen ion that is added 
A)  they obey LeChatlier's principle 
B)  weak acids cannot change the pH of a solution 
C)  weak bases added to strong bases neutralize each other 
D)  they destroy the hydrogen ion that is added

Question 4

Which of the following molecules has polar bonds but is itself not polar?

Accepted Answer

A)  NH3 
B)  CO2 
C)  CH4 
D)  H2O 
A)  NH3 
B)  CO2 
C)  CH4 
D)  H2O

Question 5

How do hydrogen bonds tend to affect the melting and boiling points of substances?

Accepted Answer

A)  They tend to increase both melting and boiling points. 
B)  They tend to decrease both melting and boiling points. 
C)  They tend to increase melting points and decrease boiling points. 
D)  They tend to decrease melting points and increase boiling points. 
E)  They do not have any affect on either melting or boiling points. 
A)  They tend to increase both melting and boiling points. 
B)  They tend to decrease both melting and boiling points. 
C)  They tend to increase melting points and decrease boiling points. 
D)  They tend to decrease melting points and increase boiling points. 
E)  They do not have any affect on either melting or boiling points.

Question 6

A buffer solution at pH 10 has a ratio of [HA]\[A − ] of 10. What is the pKa of the acid?

Accepted Answer

A)  8 
B)  9 
C)  10 
D)  11 
E)  12 
A)  8 
B)  9 
C)  10 
D)  11 
E)  12

Question 7

Exhibit 2A The structure of ATP with various groups labeled. Group III is the entire phosphate group.  
Refer to Exhibit 2A. Which of the functional groups cannot function as a hydrogen donor to water?

Accepted Answer

A)  I 
B)  II 
C)  III 
D)  IV 
E)  All can donate a hydrogen to water. 
A)  I 
B)  II 
C)  III 
D)  IV 
E)  All can donate a hydrogen to water.

Question 8

The inflection point of the titration curve for a weak monoprotic acid is equal to its pKa

Accepted Answer

A) True 
 B)False

Question 9

Bases are

Accepted Answer

A)  proton donors. 
B)  proton acceptors. 
C)  hydrogen bond donors. 
D)  hydrogen bond acceptors. 
A)  proton donors. 
B)  proton acceptors. 
C)  hydrogen bond donors. 
D)  hydrogen bond acceptors.

Question 10

Which of the following is a true statement?

Accepted Answer

A)  most substances contract when they freeze. 
B)  water expands when it freezes. 
C)  hydrogen bonding is related to water's tendency to expand as it freezes. 
D)  all of these are true 
A)  most substances contract when they freeze. 
B)  water expands when it freezes. 
C)  hydrogen bonding is related to water's tendency to expand as it freezes. 
D)  all of these are true

Question 11

A hydrogen bond is a special type of

Accepted Answer

A)  dioole - dipole bond 
B)  induced dipole - induced dipole bond 
C)  covalent bond 
D)  ionic bond 
A)  dioole - dipole bond 
B)  induced dipole - induced dipole bond 
C)  covalent bond 
D)  ionic bond

Question 12

Exhibit 2B Contains information on the pK's of some common buffers.   Refer to Exhibit 2B. A carbonate buffer would work well at this pH:

Accepted Answer

A)  4.0 
B)  6.0 
C)  8.0 
D)  10.0 
E)  6.0 and 10.0 
A)  4.0 
B)  6.0 
C)  8.0 
D)  10.0 
E)  6.0 and 10.0

Question 13

Exhibit 2B Contains information on the pK's of some common buffers.   Refer to Exhibit 2B. A phosphate buffer would work well at this pH:

Accepted Answer

A)  5.0 
B)  7.0 
C)  8.0 
D)  10.0 
E)  7.0 and 8.0 
A)  5.0 
B)  7.0 
C)  8.0 
D)  10.0 
E)  7.0 and 8.0

Question 14

If atoms with greatly differing electronegativities form a bond, that bond will be

Accepted Answer

A)  polar. 
B)  nonpolar. 
C)  amphipathic. 
D)  acidic. 
A)  polar. 
B)  nonpolar. 
C)  amphipathic. 
D)  acidic.

Question 15

Which of the following elements has the highest electronegativity?

Accepted Answer

A)  C 
B)  H 
C)  N 
D)  O 
E)  P 
A)  C 
B)  H 
C)  N 
D)  O 
E)  P

Question 16

Using the Henderson-Hasselbalch equation, calculate the pH of an ammonia buffer when the NH3:NH4+ ratio is 0.4 moles:0.6 moles. (pK = 9.75)

Accepted Answer

A)  7.40 
B)  9.07 
C)  9.25 
D)  9.43 
E)  11.05 
A)  7.40 
B)  9.07 
C)  9.25 
D)  9.43 
E)  11.05

Question 17

In a titration of a weak acid by a strong base

Accepted Answer

A)  two equivalents of base are always needed to neutralize all the acid present 
B)  the equivalence point cannot be defined exactly 
C)  there is a region in which the pH changes slowly 
D)  the equivalence point depends on the nature of the added base 
A)  two equivalents of base are always needed to neutralize all the acid present 
B)  the equivalence point cannot be defined exactly 
C)  there is a region in which the pH changes slowly 
D)  the equivalence point depends on the nature of the added base

Question 18

Calculate the final pH of a solution made by the addition of 10 mL of a 0.5 M NaOH solution to 500 mL of a 0.4 M HA originally at pH = 5.0 (pKa = 5.0) Neglect the volume change.

Accepted Answer

A)  6.10 
B)  5.09 
C)  7.00 
D)  5.55 
A)  6.10 
B)  5.09 
C)  7.00 
D)  5.55

Question 19

Molecules which contain both hydrophilic and hydrophobic regions are:

Accepted Answer

A)  Amphipathic 
B)  Amphiphilic 
C)  Able to form micelles 
D)  Both amphipathic and amphiphilic 
E)  All of these 
A)  Amphipathic 
B)  Amphiphilic 
C)  Able to form micelles 
D)  Both amphipathic and amphiphilic 
E)  All of these

Question 20

If the pH of 1 liter of a 1.0 M carbonate buffer is 7.0, what is actual number of moles of H2CO3 and HCO3 − ? (pK = 6.37)

Accepted Answer

A)  I 
B)  II 
C)  III 
D)  IV 
E)  V 
A)  I 
B)  II 
C)  III 
D)  IV 
E)  V

Exam 2: Water the Solvent for Biochemical Reactions

Which of the following molecules will not form hydrogen bonds?

An ammonia buffer contains NH3:NH4+ in a ratio of 0.4 moles:0.6 moles (pK = 9.75). What will be the pH if you add 0.01 moles of HCl to this buffer?

Buffers work to maintain pH because

Which of the following molecules has polar bonds but is itself not polar?

How do hydrogen bonds tend to affect the melting and boiling points of substances?

A buffer solution at pH 10 has a ratio of [HA] \[A − ] of 10. What is the pKa of the acid?

Exhibit 2A The structure of ATP with various groups labeled. Group III is the entire phosphate group. Refer to Exhibit 2A. Which of the functional groups cannot function as a hydrogen donor to water?

The inflection point of the titration curve for a weak monoprotic acid is equal to its pKa

Bases are

Which of the following is a true statement?

A hydrogen bond is a special type of

Exhibit 2B Contains information on the pK's of some common buffers. Refer to Exhibit 2B. A carbonate buffer would work well at this pH:

Exhibit 2B Contains information on the pK's of some common buffers. Refer to Exhibit 2B. A phosphate buffer would work well at this pH:

If atoms with greatly differing electronegativities form a bond, that bond will be

Which of the following elements has the highest electronegativity?

Using the Henderson-Hasselbalch equation, calculate the pH of an ammonia buffer when the NH3:NH4+ ratio is 0.4 moles:0.6 moles. (pK = 9.75)

In a titration of a weak acid by a strong base

Calculate the final pH of a solution made by the addition of 10 mL of a 0.5 M NaOH solution to 500 mL of a 0.4 M HA originally at pH = 5.0 (pKa = 5.0) Neglect the volume change.

Molecules which contain both hydrophilic and hydrophobic regions are:

If the pH of 1 liter of a 1.0 M carbonate buffer is 7.0, what is actual number of moles of H2CO3 and HCO3 − ? (pK = 6.37)

Biochemistry and the Organization of Cells

Amino Acids and Peptides

The Three Dimensional Structure of Proteins

Protein Purification and Characterization Techniques

The Behavior of Proteins Enzymes

The Behavior of Proteins Enzymes Mechanisms and Control

Lipids and Proteins Are Associated in Biological Membranes

Nucleic Acids How Structure Conveys Information

Biosynthesis of Nucleic Acids Replication

Transcription of the Genetic Code the Biosynthesis of Rna

Protein Synthesis Translation of the Genetic Message

Nucleic Acid Biotechnology Techniques

Viruses Cancer and Immunology

The Importance of Energy Changes and Electron Transfer in Metabolism

Carbohydrates

Glycolysis

Storage Mechanisms and Control in Carbohydrate Metabolism

The Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Lipid Metabolism

Photosynthesis

The Metabolism of Nitrogen

Integration of Metabolism Cellular Signaling

Filters

An ammonia buffer contains NH₃:NH₄⁺ in a ratio of 0.4 moles:0.6 moles (pK = 9.75). What will be the pH if you add 0.01 moles of HCl to this buffer?

A buffer solution at pH 10 has a ratio of [HA] \[A⁻] of 10. What is the pK_a of the acid?

The inflection point of the titration curve for a weak monoprotic acid is equal to its pK_a

Using the Henderson-Hasselbalch equation, calculate the pH of an ammonia buffer when the NH₃:NH₄⁺ ratio is 0.4 moles:0.6 moles. (pK = 9.75)

If the pH of 1 liter of a 1.0 M carbonate buffer is 7.0, what is actual number of moles of H₂CO₃ and HCO₃⁻? (pK = 6.37)