Question 1

When does a weak acid buffer best?

Accepted Answer

A)   From one pH unit below its pKa to its pKa.
B)   From its pKa to one pH unit above its pKa.
C)   Within one pH unit of its pKa, both above and below.
D)   Weak acids do not make good buffers at all.E) A) and B)
F) A) and C)

Question 2

The substance most likely to form a micelle is

Accepted Answer

A)   acetic acid
B)   sodium palmitate
C)   methyl alcohol
D)   acetoneE) B) and C)
F) A) and D)

Question 3

Which of the following molecules is polar?

Accepted Answer

A)   CCl4
B)   CH4
C)   CO2
D)   NH3
E)   None of these molecules is polar.F) A) and D)
G) C) and D)

Question 4

Which of the following is true about ionic compounds?

Accepted Answer

A)   They are more likely to dissolve in non-polar solvents than covalent compounds.
B)   They always dissolve completely in water.
C)   They never dissolve in polar solvents.
D)   Some of them dissolve completely in water or other polar solvents, while others do not.E) None of the above
F) All of the above

Question 5

Hydrogen bonds can only form when the hydrogen atom is involved in a polar bond.

Accepted Answer

A) True 
 B)False

Question 6

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

Accepted Answer

A) True 
 B)False  True

Question 7

A buffer solution

Accepted Answer

A)   is used to control the pH of a solution
B)   contains at least 100 times more of a weak acid than its conjugate base
C)   contains at least 100 times less of a weak acid than its conjugate base
D)   always has a pH of 7E) None of the above
F) All of the above

Question 8

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)   12F) A) and C)
G) All of the above

Question 9

Exhibit 2B Contains information on the pK's of some common buffers.
2CO3 and NaHCO3 D)  Na2HPO4 and NaH2PO4 E)  NaHCO3 and Na2CO3" class="answers-bank-image d-inline" rel="preload" > Refer to Exhibit 2B.Which of the following would make the best buffer at pH =10.0?

Accepted Answer

A)   Acetic acid and sodium acetate
B)   Tris and its acid form
C)   H2CO3 and NaHCO3
D)   Na2HPO4 and NaH2PO4
E)   NaHCO3 and Na2CO3F) C) and E)
G) None of the above E

Question 10

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)  2CO3 and HCO3-? (pK = 6.37)    A)  I B)  II C)  III D)  IV E)  V" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   I
B)   II
C)   III
D)   IV
E)   VF) None of the above
G) A) and B)

Question 11

The tendency for an atom to attract electrons to itself in a chemical bond is called

Accepted Answer

A)   polarity.
B)   electronegativity.
C)   hydrophilicity
D)   electrophilicity.E) A) and D)
F) A) and C)

Question 12

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

Accepted Answer

A)   5.6
B)   7.0
C)   9.0
D)   11.0
E)   None of theseF) B) and D)
G) B) and C)

Question 13

If a solution has a pH = 6,the [H+] is

Accepted Answer

A)   6 M
B)   106 M
C)   10-6 M
D)   0.6 ME) All of the above
F) B) and C)

Question 14

In a hydrogen bond

Accepted Answer

A)   three atoms lie in a straight line
B)   there is stronger bonding than in a covalent bond
C)   unpaired electrons play no role
D)   none of the aboveE) A) and D)
F) A) and C)

Question 15

The water molecule is polar because:

Accepted Answer

A)   Electrons are not distributed symmetrically in the molecule.
B)   The hydrogen atoms are found on one "side" of the molecule.
C)   Hydrogen is less electronegative than oxygen.
D)   The hydrogen atoms are found on one "side" of the molecule and hydrogen is less electronegative than oxygen.
E)   All of these are correct.F) A) and E)
G) B) and D)

Question 16

Which of the following is true?

Accepted Answer

A)   The pH of a solution where the A- to HA ratio is 1 has a pH = pKa.
B)   If the pH does not equal the pKa, the solution is not a buffer.
C)   The best buffer for any experiment will always have a pH equal to the pKa.
D)   If a buffer has more weak acid than conjugate base, the pH will be higher than the pKa.E) None of the above
F) C) and D)

Question 17

What is the maximum number of hydrogen bonds a single water molecule can form?

Accepted Answer

A)   1
B)   2
C)   3
D)   4
E)   5F) A) and B)
G) B) and E)

Question 18

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

Accepted Answer

A)   polar.
B)   nonpolar.
C)   amphipathic.
D)   acidic.E) A) and D)
F) A) and C) A

Question 19

Molecules which contain both hydrophilic and hydrophobic regions are:

Accepted Answer

A)   Amphipathic
B)   Detergents
C)   Able to form micelles
D)   Both amphipathic and detergents.
E)   All of theseF) B) and E)
G) D) and E)

Question 20

The ion product constant for water (Kw)  is equal to:

Accepted Answer

A)   1014
B)   107
C)   100
D)   10-7
E)   10-14F) A) and E)
G) A) and B)

Exam 2: Water: The Solvent for Biochemical Reactions

When does a weak acid buffer best?

Correct AnswerverifiedShow Answer

The substance most likely to form a micelle is

Correct AnswerverifiedShow Answer

Which of the following molecules is polar?

Correct AnswerverifiedShow Answer

Which of the following is true about ionic compounds?

Correct AnswerverifiedShow Answer

Hydrogen bonds can only form when the hydrogen atom is involved in a polar bond.

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedTrue

A buffer solution

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Exhibit 2B Contains information on the pK's of some common buffers. Refer to Exhibit 2B.Which of the following would make the best buffer at pH =10.0?

Correct AnswerverifiedE

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)

Correct AnswerverifiedShow Answer

The tendency for an atom to attract electrons to itself in a chemical bond is called

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

If a solution has a pH = 6,the [H+] is

Correct AnswerverifiedShow Answer

In a hydrogen bond

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The water molecule is polar because:

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Which of the following is true?

Correct AnswerverifiedShow Answer

What is the maximum number of hydrogen bonds a single water molecule can form?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedA

Molecules which contain both hydrophilic and hydrophobic regions are:

Correct AnswerverifiedShow Answer

The ion product constant for water (Kw) is equal to:

Correct AnswerverifiedShow Answer

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

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True

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

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E

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)

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If a solution has a pH = 6,the [H⁺] is

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A

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The ion product constant for water (K_w) is equal to:

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