ANALYTICAL CHEMISTRY Flashcards by John Clavines Edradan

How many grams of nickel (II) nitrate
hexahydrate must be used to prepare a
200ml solution containing 0.5M nitrate ions?
Assume 100% ionization. (Ni=58.69)

a. 14.53g
b. 35.41g
c. 41.35g
d. 53.14g

a. 14.53g

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A 30% solution of phosphoric acid (97.9956)
has a specific gravity of 1.18. What is its
normality as an acid assuming partial
neutralization to HPO4
2-
?

a. 3.61N
b. 7.22N
c. 4.82N
d. 9.63N

b. 7.22N

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How many mL of 1N AgNO3 would be
required to precipitate the chloride from
20mL of 0.55N SrCl26H2O?

a. 11mL
b. 5.5mL
c. 3.5mL
d. 14mL

a. 11mL

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How much water must be added to a 0.4N
solution of Cr2(SO4)318H2O in order to make it
0.05M? The solution is to be used in the
precipitation of chromium as the hydroxide.

a. 40mL
b. 62.2mL
c. 16.7mL
d. 25.5mL

c. 16.7mL

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An aqueous solution containing 20wt% KI
(166.002) has a density of 1.168g/mL. Find
the molality of the KI solution.

a. 1.24m
b. 1.05m
c. 1.65m

d. 1.51m

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The concentration of icosane (282.56) in a particular sample of rainwater is 0.2ppb.
What is its molar concentration?

a. 5x10-10M

b. 7x10-10M
c. 9x10-10M
d. 8x10-10M

b. 7x10-10M

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What is the density of 53.4% NaOH (40) if
16.7mL of the solution diluted to 2L gave
0.169M NaOH?

a. 1.52g/mL
b. 1.32g/mL

c. 0.97g/mL

d. 1.21g/mL

a. 1.52g/mL

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How many grams of B(OH)3 (61.83) should be
used to make 2L of 0.05M solution?

a. 5.21g
b. 6.18g
c. 3.44g
d. 8.32g

b. 6.18g

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Marie Curie dissolved 0.09192g of RaCl2 and treated with excess AgNO3 to precipitate
0.0889g of AgCl. In her time, the atomic mass
of Ag was known to be 107.8 and that of Cl
was 35.4. Find the atomic mass of Ra from
these values.

a. 225.6
b. 225.8
c. 225.3
d. 225.1

c. 225.3

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A method to measure soluble organic
carbon in seawater includes oxidation of the
organic materials to CO2 with K2S2O8,
followed by a gravimetric determination of
the CO2 trapped by a column of ascarite. A
water sample weighing 6.234g produced
2.378mg CO2 (44.009). Determine the ppm
C in the seawater.

a. 442.5
b. 104.1
c. 612.7
d. 242.1

b. 104.1

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Twenty dietary iron tablet total mass of
22.131g were ground and mixed
thoroughly. Then, 2.998g of the powder
were dissolved in HNO3 and treated to
convert all iron to Fe3+. Addition of NH3 precipitated Fe2O3·xH2O, which was ignited
to give 0.264g of Fe2O3 (159.69). What is the
average mass of FeSO47H2O (278.01) in each
tablet?

a. 0.512g
b. 0.339g
c. 0.155g
d. 0.769g

b. 0.339g

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The amount of calcium present in milk can
be determined by adding oxalate to a
sample and measuring the mass of calcium
oxalate precipitated. What is the mass
percent of calcium, if 0.429g of calcium
oxalate formsin a 125g sample of milk when
excess aqueous sodium oxalate is added.

Na2C2O4 (aq) + Ca+2 (aq) -> CaC2O4(S) + 2Na+
(aq)
Atomic wts.: Na=23 Ca=40 C=12 O=16

a. 0.11%
b. 0.22%
c. 0.33%
d. 0.44%

a. 0.11%

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One pound of a mixture of NaCl and KCl was
water treated with sulfuric acid and 1.2lb of
potassium and sodium sulfate were
recovered. What is the mass ratio of NaCl
to KCl in the original mixture?

a. 2.14
b. 2.41
c. 4.12
d. 4.21

a. 2.14

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A solid mixture weighing 0.5485g contained
only ferrous ammonium sulfate
hexahydrate, FeSO4(NH4)2SO4 6H2O (392.13)
and ferrous chloride hexahydrate, FeCl2
6H2O (234.840). The sample was dissolved
in 1M H2SO4, oxidized to Fe3+ with H2O2, and
precipitated with cupferron. The ferric
cupferron complex was ignited to produce
0.1678g of ferric oxide (159.69). Calculate
the wt% Cl (35.453) in the original sample.

a. 41.15%
b. 13.7%
c. 64.12%
d. 22.65%

d. 22.65%

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(Nov. 2019 PBE) Determine the molarity of
a solution prepared in the laboratory by
dissolving 12.7g of HCl in sufficient water to
make 1L of solution.

a. 0.1277M
b. 0.5221M
c. 0.3481M
d. 0.4231M

c. 0.3481M

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(Oct. 2021 PBE) Determine the number of
moles and grams of N2HPO4 in 1.75L in
0.46M of NaHPO4 solution.

a. 0.556mol; 85g
b. 0.805mol; 114g
c. 0.46mol; 185g
d. 0.656mol; 90g

b. 0.805mol; 114g

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(Oct. 2021 PBE) Determine the number of
moles of an unknown base in a solution
when titrated with 0.15M HCl and 22.01mL
of the acid were needed to reach the end
point of the titration.

a. 2.2x10-3ml
b. 1.1x10-3ml
c. 0.9x10-3ml
d. 3.3x10-3ml

d. 3.3x10-3ml

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(Oct. 2021 PBE) If one gallon of blood was
added in three gallons of water, and one
ounce of that dilution was added to 9
ounces of water, what is the final dilution
when 7mL of that dilution was added to
563mL of water?

a. 5.65x10-3
b. 2.24x10-2
c. 1.72x10-4
d. 3.11x10-4

d. 3.11x10-4

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(Nov. 2019 PBE) Determine the final
volume of 0.51M KBr when the starter
volume is 100mL. From a 50mL solution of
0.25M alanine, what volume will be
required using 0.11M alanine?

a. 196mL; 114mL
b. 51mL; 33mL
c. 179mL; 102mL
d. 201mL; 120mL

a. 196mL; 114mL

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A solution is basic if:

a. [OH-
] > 0
b. [OH-
] = 1x10-7M
c. [OH-
] > [H+
]
d. [OH-
] > 1x10-7M

c. [OH-
] > [H+
]
d. [OH-
] > 1x10-7M

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Water at room temperature usually has a slightly
acidic pH. This is largely attributed to what
compound(s)?

a. Sulfuric acid
b. Dissolved metals
c. Carbonic acid
d. Nitric acid

c. Carbonic acid

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When benzoic acid dissolves in water, it partially
reacts with water and ionizes to form benzoate
and hydronium ions. In this reaction, what is the
conjugate acid?

a. Benzoate ions
b. Hydronium ions
c. Water
d. Benzoic acid

b. Hydronium ions

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Define a salt in terms of acid and base.

a. A salt is a compound that follows Le
Chatelier’s Principle in reactions with
other compounds.
b. All of these
c. A salt is a compound formed when the
nucleus of a hydrogen tom enters a
quantity of water.
d. A salt is a compound (other than water)
produced by the reaction of an acid and
a base.

d. A salt is a compound (other than water)
produced by the reaction of an acid and
a base.

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When a can ofsoda is opened and CO2 isreleased
to the atmosphere, what is the resultant pH of
the soda?

a. Decreases
b. Increases
c. The same
d. All these

b. Increases

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What is the pH of a 0.035M KOH solution? a. 12.54 b. 1.46 c. 3.5 d. 9.97

a. 12.54

BHClO4 is a salt formed from the weak base B (Kb=1x10-4 ) and perchloric acid, a strong acid. Find the pH of 0.1M BHClO4. a. 5.5 b. 2.15 c. 8.93 d. 10.1

a. 5.5

A 0.045M solution of benzoic acid has a pH of 2.78. Calculate its pKa. a. 6.75 b. 2.15 c. 5.77 d. 4.2

d. 4.2

A 0.1M solution of a base has pH=9.28. Find Kb. a. 5.2x10-8 b. 3.6x10-9 c. 4.4x10-6 d. 1.7x10-5

b. 3.6x10-9

A 0.1M solution of a base is 2% hydrolyzed. Find Kb. a. 2.4x10-8 b. 5.5x10-9 c. 3.1x10-7 d. 4.1x10-5

d. 4.1x10-5

A 10.231g sample of window cleaner containing ammonia was diluted with 39.466g of water. Then 4.373g of solution were titrated with 14.22mL of 0.1063M HCl to reach a bromocresol green endpoint. Find the weight % of NH3 (17.031) in the cleaner. a. 10.9% b. 16.3% c. 5.33% d. 2.86%

d. 2.86%

(Nov. 2019 PBE) In a titration experiment, 15.02mL of an HCl solution required 26.1mL of 0.32M sodium hydroxide. Determine the concentration of HCl. a. 2.15M b. 0.52M c. 1.12M d. 0.64M

b. 0.52M

Find the pH at the following points in the titration of 30mL of 0.05M HClO4 with 0.1M KOH. When 5mL of 0.1M KOH is added a. 1.54 b. 2.54 c. 3.54 d. 4.54 When 15mL of 0.1M KOH is added a. 5 b. 6 c. 7 d. 8 When 20mL of 0.1M KOH is added a. 9 b. 10 c. 11 d. 12

a. 1.54 c. 7 d. 12

Find the pH at the following points in the titration of 50mL of 0.02M KOH with 0.1M HBr. When 3mL of 0.1M HBr is added a. 10.12 b. 11.12 c. 12.12 d. 13.12 When 10mL of 0.1M HBr is added a. 6 b. 7 c. 8 d. 9 When 10mL of 0.1M HBr is added a. 6 b. 7 c. 8 d. 9 When 10.5mL of 0.1M HBr is added a. 3.08 b. 4.08 c. 5.08 d. 6.08

c. 12.12 b. 7 a. 3.08

Find the pH at the following points in the titration of 25mL of 0.3M HF with 0.3M NaOH. The KA value is 6.6x10-4 After adding 10mL of 0.3M NaOH a. 2 b. 3 c. 4 d. 5 After adding 12.5mL of 0.3M NaOH a. 2.18 b. 3.18 c. 4.18 d. 5.18 After adding 25mL of 0.3M NaOH a. 7.18 b. 8.18 c. 9.18 d. 10.18 After adding 26mL of 0.3M NaOH a. 10.77 b. 11.77 c. 12.77 d. 13.77

b. 3 b. 3.18 b. 8.18 b. 11.77

You are given 90 mL of 0.6 M of the weak base NH3 (Kb = 1.8 × 10-5 ), and 1 M of the strong acid titrant HCl. What is the pH after 50 mL of acid is added? a. 6.16 b. 7.16 c. 8.16 d. 9.16 What is the pH at the equivalence point? a. 3.84 b. 4.84 c. 5.84 d. 6.84 What is the pH after 60 mL of acid is added? a. 1.4 b. 2.4 c. 3.4 d. 4.4

c. 8.16 b. 4.84 a. 1.4

Which of the following pairs will form a buffer solution in the course of a titration? a. Nitric acid, sodium hydroxide b. Sulfuric acid, potassium hydroxide c. Acetic acid, sodium hydroxide d. Hydrochloric acid, potassium hydroxide

c. Acetic acid, sodium hydroxide

Buffer capacity is maximum when: a. pH = 0.5pKa b. pH = pKa c. pH = 2pKa d. pH = 0.1pKa

b. pH = pKa

Which of the following acids would be most suitable for preparing a buffer of pH 3.1? a. Hydrogen peroxide, pKa = 11.65 b. Propanoic acid, pKa = 4.874 c. Cyanoacetic acid, pKa = 2.472 d. Sulfanilic acid, pKa = 3.232

d. Sulfanilic acid, pKa = 3.232

How many grams of Na2CO3 (105.99) should be mixed with 5g of NaHCO3 (84.01) to produce 100mL of buffer with pH 10? pKa1=6.351, pKa2=10.329. a. 2.96g b. 2.02g c. 2.56g d. 2.34g

a. 2.96g

How many mL of 0.246M HNO3 should be added to 213mL of 0.00666M 2,2’- bipyridine (pKa = 4.34) to give a pH of 4.19? a. 2.25mL b. 6.44mL c. 3.38mL d. 8.1mL

c. 3.38mL

What is the pH at the equivalence point when 0.1M hydroxyacetic acid (pKa=3.832) is titrated with 0.05M KOH? a. 2.56 b. 4.75 c. 10.2 d. 8.18

d. 8.18

(Nov. 2019 PBE) Determine the: • Moles of analyte • Volume of titrant to reach end point • pH at the start, halfway and at the endpoint for each of the titrations performed. For the titration shown as follows: 50mL of a weak base (pKb=5), 0.072M with 0.153M HCl. a. 3x10-3mol; 24mL; 10.84, 8.82, 5.06 b. 11.25x10-4mol; 12.22mL; 7.34, 2.11, 12.23 c. 10.35x10-1mol; 16mL; 5.32, 4.23, 8.45 d. 7.24x10-2mol; 11.25mL; 11.23, 5.31, 9.56

a. 3x10-3mol; 24mL; 10.84, 8.82, 5.06

(Oct. 2021 PBE) Determine the pH of a 0.21M solution ofsodium benzoate in water at room temperature. (KA=6.3x10-5 ) a. 6.35 b. 4.37 c. 0.74 d. 2

c. 0.74

(Nov. 2019 PBE) Determine the pH of a 0.05M solution of each salt: • Potassium acetate (KA=1.8x10-5 ) • Sodium benzoate • Potassium carbonate • Sodium dihydrogen phosphate • Ammonium nitrate a. 11.5, 8.45, 4.56, 4.26, 1.23 b. 10.65, 3.22, 11, 8.45, 5.27 c. 8.45, 4.26, 7, 11.5, 8.73 d. 8.73, 5.99, 8.45, 7.33, 7

d. 8.73, 5.99, 8.45, 7.33, 7

(Oct. 2021 PBE) When formic acid is 4.6% ionized in 0.105M of aqueous solution at room temperature, determine the ionization constant of the acid. If the solution containing 0.25N of 25mL acid is diluted to 202mL and titrated with 0.35 NaOH, calculate the pH value and the concentration of the hydrogen ion at the equivolume part. a. 2.2x10-4 ; 8.06; 8.7x10-9 b. 1.8x10-5 ; 9.1; 7.2x10-10 c. 4.1x10-4 ; 7.21; 6.4x10-10 d. 3.4x10-4 ; 6.32; 5.23x10-11

a. 2.2x10-4 ; 8.06; 8.7x10-9

(Oct. 2021 PBE) A solution of HCl and a monobaric acid is titrated with NaOH. If the initial volume of the solution is 100mL and the concentration of each moment is 0.011M and the ionization constant is 1.01x105 and the concentration of the titrant base is 0.1M, estimate the pH of the solution when 5mL and 15mL of the titrate has been added and the optimum pKa of a weak acid indicator to allow determination of the HCl present. a. 2.3, 5.0, 3.5 b. 3.7, 6.0, 4.5 c. 3.4, 4.5, 5.2 d. 4.2, 7.0, 6.2

a. 2.3, 5.0, 3.5

The Kjeldahl procedure was used to analyze 256 microliters of a solution containing 37.9mg/mL protein. The liberated NH3 (17.031) was collected in 5mL of 0.0336M HCl, and the remaining acid required 6.34mL of 0.01M NaOH for complete titration. What is the weight % of nitrogen (14.007) in the protein? a. 55.2% b. 15.1% c. 95.6% d. 67.2%

b. 15.1%

The formaldehyde content of a pesticide preparation was determined by weighing 0.2985g of the liquid sample into a flask containing 50mL of 0.0959M NaOH and 50mL of 3% H2O2. Upon heating, the formaldehyde was oxidized to acetate, consuming the base in a 1:1 ratio. After cooling, the excess base was titrated with 22.71mL of 0.0537M H2SO4. Calculate the percentage of formaldehyde (30.026) in the sample. a. 11.5% b. 45.6% c. 75.2% d. 23.7%

d. 23.7%

(Oct. 2021 PBE) If the normality of HCl is greater by 10% compared to KOH, estimate the normality of the HCl solution when 0.67g of (NH4)2SO4 is dissolved in water, treated with excess NaOH and the ammonia released is passed through a solution of 20mL of HCl. The excess acid solution is titrated using 15.01mL of KOH solution. a. 0.275N b. 3.17x10-3N c. 0.152N d. 2.32x10-2N

c. 0.152N

A solution contains NaHCO3, Na2CO3, and NaOH, either alone or in permissible combination. Titration of a 50mL portion to a phenolphthalein endpoint requires 22.1mL of 0.1M HCl. A second aliquot requires 48.4mL of the HCl when titrated to a bromocresol green endpoint. Determine the composition in terms of molar solute concentrations of the original solution. a. 0.0084M Na2CO3, 0.0442M NaHCO3 b. 0.0442M Na2CO3, 0.0084M NaHCO3 c. 0.0084M Na2CO3, 0.0442M NaOH d. 0.0442M Na2CO3, 0.0084M NaOH

b. 0.0442M Na2CO3, 0.0084M NaHCO3

A series of solutions containing NaOH, Na CO , and NaHCO3, alone or in compatible combinations, was titrated with 0.1202M HCl. Shown in the table are the volumes of acid needed to titrate 25mL portions of each solution to a phenolphthalein (1) and a bromocresol green (2) endpoint. Solution V1 V2 S1 22.42 22.44 S2 15.67 42.13 S3 29.64 36.42 S4 16.12 32.23 S5 0 33.33 Which solution contains only Na2CO3? a. S1 b. S3 c. S4 d. S2 Which solution contains Na2CO3 and NaOH? a. S1 b. S3 c. S4 d. S2 For the solution that contains Na2CO3 and NaHCO3, calculate the mass of Na2CO3 (105.99) present. a. 199.6mg b. 536.7mg c. 337.1mg d. 477.6mg

c. S4 b. S3 a. 199.6mg

1.906g of soda ash is dissolved in 500ml of water. Using parallel titration method, the 50ml aliquot needed 15.6ml of 0.10N HCl for the phenolphthalein endpoint and 28.8ml of 0.10N HCl to reach the methyl orange endpoint. What is the weight percent of NaOH, Na2CO3, and NaHCO3 present in the sample? Use correct number of significant digits. O = 16, C = 12, H = 1, Na = 23 a. Na2CO3 = 5.04% and NaOH = 73.41% b. Na2CO3 = 26.59% and NaOH = 73.41% c. Na2CO3 = 73.41% and NaOH = 5.04% d. Na2CO3 = 73.41% and NaOH = 26.59%

c. Na2CO3 = 73.41% and NaOH = 5.04%

A 30mL solution of HBr was treated with 5mL of freshly boiled and cooled 8M HNO3, and then with 50mL of 0.365M AgNO3 with rigorous stirring. Then, 1mL of saturated ferric alum was added and the solution was titrated with 0.287M KSCN. When 3.6mL had been added, the solution turned red. What was the molar concentration of HBr in the original solution? a. 0.5739M b. 0.3395M c. 0.2724M d. 0.6788M

a. 0.5739M

A silver nitrate solution contains 14.77g of primary-standard AgNO3 (169.87) in 1L. What volume of the solution will be needed to react with 0.2631g of NaCl (58.44)? a. 28.54mL b. 51.78mL c. 63.34mL d. 79.81mL

b. 51.78mL

A mixture of pure LiCl (42.394) and BaI2 (391.136) weighing 0.6g is treated with 45.15mL of 0.2M AgNO3 solution, and the excess silver is then titrated with 25mL of KSCN at 0.1M with ferric alum as an indicator. Find the percentage of iodine (126.904) in the mixture. a. 54.1% b. 88.5% c. 23.5% d. 44.6%

d. 44.6%

(Oct. 2021 PBE) Analyze and calculate the percentage of nickel in a 1.201g sample of nickel ore which was analyzed by the volumetric method. A solution of 48mL containing 1.4x10-2 g of KCN/mL and the excess cyanide required half a milliliter of silver nitrate solution with 1.25x10-2 g AgNO3 per milliliter. a. 9.36% b. 15.21% c. 12.5% d. 8.22%

c. 12.5%

A 50mL sample of Ni2+ was treated with 25mL of 0.05M EDTA to complex all the Ni2+ and leave excess EDTA in solution. The excess EDTA was then back-titrated, requiring 5mL of 0.05M Zn2+. What was the concentration of Ni2+ in the original solution? a. 0.0125M b. 0.05M c. 0.02M d. 0.01M

c. 0.02M

Ni2+ can be analyzed by a back titration by using standard Zn2+ with xylenol orange indicator. A solution containing 25mL of Ni2+ is treated with 25mL of 0.05283M Na2EDTA. The solution turns yellow when a few drops of indicator are added. Titration with 0.02299M Zn2+ requires 17.61mL to reach the red endpoint. What is the molarity of Ni2+ in the unknown? a. 0.03664M b. 0.04663M c. 0.06346M d. 0.06436M

a. 0.03664M

Cyanide solution (12.73mL) was treated with 25mL of Ni2+ solution in excess to convert the cyanide to tetracyanonickelate (II). Excess Ni2+ was then titrated with 10.15mL of 0.01307M EDTA. If 39.35mL of EDTA were required to reach equilibrium with 30.1mL of the original Ni2+ solution, calculate the molarity of CN- in the 12.73mL sample. a. 0.09254M b. 0.04415M c. 0.03256M d. 0.02313M

a. 0.09254M

A 50mL solution containing Ni2+ and Zn2+ was titrated with 25mL of 0.0452M EDTA to bind all the metal. The excess unreacted EDTA required 12.4mL of 0.0123M Mg2+ for complete reaction. An excess of the reagent 2,3-dimercapto-1-propanol was then added to displace the EDTA from zinc. Another 29.2mL of Mg2+ were required for reaction with the liberated EDTA. Calculate the molarity of Ni2+ in the original solution. a. 0.0072M b. 0.0124M c. 0.0685M d. 0.0414M

b. 0.0124M

A 25mL sample containing Fe3+ and Cu2+ required 16.06mL of 0.05083M EDTA for complete titration. A 50mL sample of the unknown was treated with NH4F to protect the Fe3+ . Then Cu2+ was reduced and masked by thiourea. Addition of 25mL of 0.05083M EDTA liberated Fe3+ from its fluoride complex to form an EDTA complex. The excess EDTA required 19.77mL of 0.01883M Pb2+ to reach a xylenol orange endpoint. Find [Cu2+] in the unknown. a. 0.01468M b. 0.04186M c. 0.06814M d. 0.08641M

a. 0.01468M

Calculate the weight of primary standard Na2C2O4 (134g/mol) necessary to react with 25mL of 0.2005M KMnO4 in acidic medium. a. 0.671g b. 1.679g c. 1.313g d. 2.687g

b. 1.679g

Aqueous glycerol (C3H8O3, 92.095) solution weighing 100mg was treated with 50mL of 0.0837M Ce4+ in 4M HClO4 at 60˚C for 15min to oxidize glycerol to formic acid, H2CO2. The excess Ce4+ required 12.11mL of 0.0448M Fe2+ to reach a ferroin endpoint. Find the weight % glycerol in the unknown. a. 86.2% b. 41.9% c. 33.1% d. 68.4%

b. 41.9%

A 50mL sample containing La3+ was treated with sodium oxalate to precipitate La2(C2O4)3, which was washed, dissolved in acid, and titrated with 18.04mL of 0.006363M KMnO4. Find [La3+] in the unknown. a. 6.123mM b. 9.314mM c. 5.523mM d. 3.826mM

d. 3.826mM

A 3.026g portion of a copper (II) salt was dissolved in a 250mL volumetric flask. A 50mL aliquot was analyzed by adding 1g of KI and titrating the iodine with 23.33mL of 0.04668M Na2S2O3. Find the wt% of Cu (63.546) in the salt. a. 53.15% b. 25.22% c. 11.43% d. 42.59%

c. 11.43%

(Oct. 2021 PBE) A certain volume of a solution of KMnO4 will oxidize sufficient potassium tetraoxalate that requires half of that volume using 0.201N of KOH solution for neutralization. Determine the quantity of KMnO4 in a liter of its solution. a. 4.213g b. 2.01g c. 8.621g d. 5.02g

b. 2.01g

(Nov. 2019 PBE) The distance of the Earth to the most remote normal galaxy is calculated to be: a. 2x10^22m b. 1.4x10^26m c. 4x10^16m d. 9x10^25m

d. 9x10^25m a. 2x10^22m NEAREST GALAXY (ANDROMEDA) b. 1.4x10^26m MOST REMOTE QUASAR c. 4x10^16m NEAREST STAR (PROXIMA CENTAURI)