Part B (Comprehensive Questions: 20 points)
36.A 1.345 g sample of a compound of barium and oxygen was dissolved in hydrochloric acid to give a solution of barium ion, which was then precipitated with an excess of potassium chromate to give 2.012 g of barium chromate, BaCrO
4
. What is the formula of the compound?(4 points)
37a. Phenol, commonly known as carbolic acid, was used by Joseph Lister as an antiseptic for surgery in 1865. Its principle use today is the manufacture of phenolic resins and plastics. Combustion of 5.23 mg of phenol yields 14.67 mg CO
2
and 3.01 mg H
2
O. Phenol contains only C, H, and O. What is the percentage of each element in this substance?(2 points)
37.b.How many milliliters of 0.250 M KMnO4 are needed to react with 4.40 g of iron(II) sulfate, FeSO
4
? (Hint: Volumetric analysis)
The reaction is as follows:
10FeSO
4
(
aq
) + 2KMnO
4
(
aq
) + 8H
2
SO
4
(
aq
)
5Fe
2
(SO
4
)
3
(
aq
) + 2MnSO
4
(
aq
) + K
2
SO
4
(
aq
) + 8H
2
O(
l
)
(2 points)
38.Two compounds have the same composition: 85.62% C and 14.38% H.
. a. Obtain the empirical formula corresponding to this composition.
b. One of the compounds has a molecular mass of 28.03 amu; the other, of 56.06 amu. Obtain the molecular formulas of both compounds.( 4 points)
39.a.For the given aqueous reaction, write the molecular and net ionic equations, including phase labels..(2 points)
The neutralization of acetic acid by calcium hydroxide, both in aqueous solution
39.b.Balance the following oxidation-reduction reaction by the half-reaction method...(2 points)
FeI
3
(
aq
) + Mg(
s
)
Fe(
s
) + MgI
2
(
aq
)
40.a.One step in the isolation of pure rhodium metal (Rh) is the precipitation of rhodium(III) hydroxide from a solution containing rhodium(III) sulfate according to the following balanced chemical equation:
Rh
2
(SO
4
)
3
(
aq
) + 6NaOH(
aq
) 2Rh(OH)
3
(
s
) + 3Na
2
SO
4
(
aq
)
What is the theoretical yield of rhodium(III) hydroxide from the reaction of 0.590 g of rhodium(III) sulfate with 0.366 g of sodium hydroxide? Show detailed work.
(3 points)
40.b. Using questions 40a, calculate the percentage yield ofrhodium(III) hydroxide, Rh(OH)3 ; given that the actual yield ofRh(OH)3 is 0.320 g.
.
Part B (Comprehensive Questions 20 points) 36.A 1.345 g sample .docx
1. Part B (Comprehensive Questions: 20 points)
36.A 1.345 g sample of a compound of barium and oxygen was
dissolved in hydrochloric acid to give a solution of barium ion,
which was then precipitated with an excess of potassium
chromate to give 2.012 g of barium chromate, BaCrO
4
. What is the formula of the compound?(4 points)
2. 37a. Phenol, commonly known as carbolic acid, was used by
Joseph Lister as an antiseptic for surgery in 1865. Its principle
use today is the manufacture of phenolic resins and plastics.
Combustion of 5.23 mg of phenol yields 14.67 mg CO
2
and 3.01 mg H
2
O. Phenol contains only C, H, and O. What is the percentage
of each element in this substance?(2 points)
3. 37.b.How many milliliters of 0.250 M KMnO4 are needed to
react with 4.40 g of iron(II) sulfate, FeSO
4
? (Hint: Volumetric analysis)
The reaction is as follows:
10FeSO
4
(
aq
) + 2KMnO
4
(
aq
) + 8H
2
SO
4
(
aq
)
5Fe
2
(SO
4
)
3
(
aq
) + 2MnSO
4
(
aq
) + K
2
SO
4. 4
(
aq
) + 8H
2
O(
l
)
(2 points)
38.Two compounds have the same composition: 85.62% C and
14.38% H.
. a. Obtain the empirical formula corresponding to this
composition.
5. b. One of the compounds has a molecular mass of 28.03 amu;
the other, of 56.06 amu. Obtain the molecular formulas of both
compounds.( 4 points)
39.a.For the given aqueous reaction, write the molecular and net
ionic equations, including phase labels..(2 points)
6. The neutralization of acetic acid by calcium hydroxide, both in
aqueous solution
39.b.Balance the following oxidation-reduction reaction by the
half-reaction method...(2 points)
FeI
3
(
aq
) + Mg(
s
)
Fe(
s
) + MgI
2
(
aq
)
7. 40.a.One step in the isolation of pure rhodium metal (Rh) is the
precipitation of rhodium(III) hydroxide from a solution
containing rhodium(III) sulfate according to the following
balanced chemical equation:
Rh
2
(SO
4
)
3
(
aq
) + 6NaOH(
aq
) 2Rh(OH)
3
(
8. s
) + 3Na
2
SO
4
(
aq
)
What is the theoretical yield of rhodium(III) hydroxide from the
reaction of 0.590 g of rhodium(III) sulfate with 0.366 g of
sodium hydroxide? Show detailed work.
(3 points)
9. 40.b. Using questions 40a, calculate the percentage yield
ofrhodium(III) hydroxide, Rh(OH)3 ; given that the actual yield
ofRh(OH)3 is 0.320 g.
