CHEM 120 FINAL EXAM Questions
And Answers Verified 100% Correct
D - ANSWER -What is the bond angle in a perfect tetrahedron
molecule like CH4?
A) 120
B) 0
C) 180
D) 109.5
A - ANSWER -When SO3 reacts water, sulfuric acid (H2SO4) is
formed. Is SO3 a BrØnsted-Lowry acid?
A) No, it is not a BrØnsted-Lowry acid.
B) Yes, it is a BrØnsted-Lowry acid.
B - ANSWER -Conjugate acid and base is a concept unique to
BrØnsted-Lowry acids and bases. Which of the pairs below are not
conjugate acid and base?
a. H2SO4 and SO42- b. H2CO3, CO2 c. HCl and Cl2 d. H3O+ and HO- e.
HBr and Br-
A) a,b,c B) a,b,c,d C) a,b D) a,b,c,d,e E) e
,C - ANSWER -What is the pH value of an acidic solution with a proton
molar concentration of 10^-3?
A) 0.001 B) 0.003 C) 3 D) -3
A - ANSWER -Gastric acid is composed of hydrochloric acid (HCl) - a
strong acid. The pH range of gastric acid is 1.5 to 3.5 in the human
stomach. If the HCl concentration is 0.5 mole/liter in John's stomach,
is the pH value of his gastric acid in the normal range, too high, or too
low?
A) Too low B) Too high C) In the normal range.
D - ANSWER -Which of the compounds below is the smallest
carboxylic acid? (Some carboxylic acids can found in Section 2.3)
58%
A) Methyl alcohol (MeOH)
B) Methylamine (CH3NH2)
C) Acetic acid
D) Formic acid
A - ANSWER -Hydronium (H3O+) has a pKa of -1.7, and is the
strongest acid that can exist in water. A carboxylic acid (RCOOH) can
be protonated by hydronium. So, the pKa of RCOOH:
A) must be greater than -1.7
B) cannot be determined
C) must be smaller than -1.7
,A - ANSWER -What is the molecular formula of carbonic acid? Is it a
strong acid? (Section 2.2)
A) H2CO3. It is a very weak acid.
B) H2CO3. It is a weak acid.
C) HCO3. It is a very weak acid.
D) CO2. It is a moderately strong acid.
A - ANSWER -Hydrochloric acid (HCl), sulfuric acid (H2SO4), nitric
acid (HNO3), and acetic acid (CH3COOH) are the most commonly
used acids. Find their pKa values in sections 2.2-2.6 (or online) and
determine which of the following sequences is in the order of
ascending acid strength.
A) CH3COOH < HNO3 < H2SO4 < HCl
B) CH3COOH < HNO3 < HCl < H2SO4
C) CH3COOH < HCl < H2SO4 < HNO3 D) HCl < H2SO4 < HNO3 <
CH3COOH
B - ANSWER -If HB1 is a stronger BrØnsted-Lowry acid than HB2
(also a BrØnsted-Lowry acid), which is more likely to be protonated
when the two are mixed?
A) HB1
B) HB2
, C) Cannot be determined
B - ANSWER -Which of the above is the correct expression for
equilibrium constant K of the acid-base reaction of acetic acid
(CH3OOH) and ammonia (NH3)?
A) a
B) b
C) c
D) d
B - ANSWER -Does the relationship between size of B (or B-) and
acidity of HB (Section 2.6) apply to the elements of the same row (e.g.,
C, N, O, F)?
A) Yes B) No
C - ANSWER -To an aqueous solution of acetic acid (CH3COOH, PKa
=4.8), NaOH is added to change the pH to 6.8. What is the ratio of
concentrations of CH3COO- and CH3COOH in the resulting solution?
(Hint: write the Ka expression for CH3COOH, from which you can
calculate the ratio using the ratio of Ka and [H])
A) -2.0 B) 2.0 C) 100 D) 0.01
And Answers Verified 100% Correct
D - ANSWER -What is the bond angle in a perfect tetrahedron
molecule like CH4?
A) 120
B) 0
C) 180
D) 109.5
A - ANSWER -When SO3 reacts water, sulfuric acid (H2SO4) is
formed. Is SO3 a BrØnsted-Lowry acid?
A) No, it is not a BrØnsted-Lowry acid.
B) Yes, it is a BrØnsted-Lowry acid.
B - ANSWER -Conjugate acid and base is a concept unique to
BrØnsted-Lowry acids and bases. Which of the pairs below are not
conjugate acid and base?
a. H2SO4 and SO42- b. H2CO3, CO2 c. HCl and Cl2 d. H3O+ and HO- e.
HBr and Br-
A) a,b,c B) a,b,c,d C) a,b D) a,b,c,d,e E) e
,C - ANSWER -What is the pH value of an acidic solution with a proton
molar concentration of 10^-3?
A) 0.001 B) 0.003 C) 3 D) -3
A - ANSWER -Gastric acid is composed of hydrochloric acid (HCl) - a
strong acid. The pH range of gastric acid is 1.5 to 3.5 in the human
stomach. If the HCl concentration is 0.5 mole/liter in John's stomach,
is the pH value of his gastric acid in the normal range, too high, or too
low?
A) Too low B) Too high C) In the normal range.
D - ANSWER -Which of the compounds below is the smallest
carboxylic acid? (Some carboxylic acids can found in Section 2.3)
58%
A) Methyl alcohol (MeOH)
B) Methylamine (CH3NH2)
C) Acetic acid
D) Formic acid
A - ANSWER -Hydronium (H3O+) has a pKa of -1.7, and is the
strongest acid that can exist in water. A carboxylic acid (RCOOH) can
be protonated by hydronium. So, the pKa of RCOOH:
A) must be greater than -1.7
B) cannot be determined
C) must be smaller than -1.7
,A - ANSWER -What is the molecular formula of carbonic acid? Is it a
strong acid? (Section 2.2)
A) H2CO3. It is a very weak acid.
B) H2CO3. It is a weak acid.
C) HCO3. It is a very weak acid.
D) CO2. It is a moderately strong acid.
A - ANSWER -Hydrochloric acid (HCl), sulfuric acid (H2SO4), nitric
acid (HNO3), and acetic acid (CH3COOH) are the most commonly
used acids. Find their pKa values in sections 2.2-2.6 (or online) and
determine which of the following sequences is in the order of
ascending acid strength.
A) CH3COOH < HNO3 < H2SO4 < HCl
B) CH3COOH < HNO3 < HCl < H2SO4
C) CH3COOH < HCl < H2SO4 < HNO3 D) HCl < H2SO4 < HNO3 <
CH3COOH
B - ANSWER -If HB1 is a stronger BrØnsted-Lowry acid than HB2
(also a BrØnsted-Lowry acid), which is more likely to be protonated
when the two are mixed?
A) HB1
B) HB2
, C) Cannot be determined
B - ANSWER -Which of the above is the correct expression for
equilibrium constant K of the acid-base reaction of acetic acid
(CH3OOH) and ammonia (NH3)?
A) a
B) b
C) c
D) d
B - ANSWER -Does the relationship between size of B (or B-) and
acidity of HB (Section 2.6) apply to the elements of the same row (e.g.,
C, N, O, F)?
A) Yes B) No
C - ANSWER -To an aqueous solution of acetic acid (CH3COOH, PKa
=4.8), NaOH is added to change the pH to 6.8. What is the ratio of
concentrations of CH3COO- and CH3COOH in the resulting solution?
(Hint: write the Ka expression for CH3COOH, from which you can
calculate the ratio using the ratio of Ka and [H])
A) -2.0 B) 2.0 C) 100 D) 0.01
