Analytical Chem (MRII)

Question 1

All of the following is used as a hygroscopic material in desiccators except
a. CaSO4
b. Mg (ClO_{4}) 2
c. P_{2}O_{5}
d. CuSO4

Answer 1

d. CuSO4

Question 2

Analytical methods classified as micro analyses use sample mass ranging from
a. < 1 mg
b. 1-10 mg
c. 10-100 mg
d.> 100mg

Answer 2

b. 1-10 mg

Question 3

Chemicals which are tested by the manufacturers showing the actual percentages of impurities and labeled on the containers are called
a. reagent grade chemicals
b. analytical reagent
c. certified reagent
d. all of these

Answer 3

d. all of these

Question 4

What proportion by weight of Na_{2}C_{2}*O_{4} (134) to that of KHC₂O, H₂C₂O, (218.2) that must be mixed in a solution so that the normality of the resulting solution as a reducing agent is three times the normality as an acid?
a. 3.07
b. 1.54
c. 0.65
d. 0.33

Answer 4

b. 1.54

Question 5

Platinum crucibles can be used for the following processes without significant loss except
a. Fusion with sodium carbonate, borax or alkali bifluorides
b. Evaporation with hydrofluoric acid
c. Ignition of oxides of Ca and Sr
d. Heating with sulfides

Answer 5

d. Heating with sulfides

Question 6

What volume of water must be added to concentrated HCl solution to prepare 100 mL 0.955 M HCl solution?
a. 7.9 mL
b. 15.8 mL
c. 46.0 mL
d. 92.1 mL

Answer 6

d. 92.1 mL

Question 7

What grade of water as defined by the British Standard 3978 is suitable for the determination of trace quantities which can be prepared by the distillation of de-ionized water?
a. Grade 1
b. Grade 2
c. Grade 3
d. Grade 4

Answer 7

b. Grade 2

Question 8

A 20% wt/wt aqueous solution of NaCl (58.45) at 25 deg * C has a density 1.145 g-mL. Express the amount of solute in this solution as follows:

8. % wt/vol
   a. 17
   b. 19
   c.21
   d. 23
9. molarity (M)
   a. 0.98
   b. 1.96
   c. 3.92
   d. 5.88
10. molality (m)
    a. 4.28
    b. 5.13
    c. 6.84
    d. 8.56

Answer 8

8. d. 23
9. c. 3.92
10. a. 4.28

Question 9

The following describes colloidal suspensions formed during precipitation except
a. These particles are almost invisible to the naked eye
b. They settle readily from a given solution
c. They are not easily filtered
d. none of the these

Answer 9

b. They settle readily from a given solution

Question 10

A 1.5176 g sample of a CaCO, was dissolved in an acidic solution. The calcium w precipitated as CaC₂O, H₂O (146.11) and the ignited precipitate at 230 deg * C was found to weigh 0.8249 g. What is the percentage of CaO (56.08) in the sample?
a. 20.9%
b. 23.8%
c. 41.8%
d. 47.6%

Answer 10

b. 23.8%

Question 11

A mixture containing FeCl, (162.20) and AlCl3 (133.33) only weighs 750.8 mg. The chlorides were precipitated using ammonia and ignited to Fc_{2}O_{3} 159.69) and Al_{2}O_{2} (101.96), respectively. The oxide mixture weighs 351.3 mg. Calculate the percentage of Al (26.98) in the sample.
a. 1.5%
b. 4.5%
c. 7.5%
d. 10.5%

Answer 11

b. 4.5%

Question 12

Which of the following does not describe the correct way to wash precipitates?
a. Minimum volume of washing liquid must be used to wash the precipitate
b. Wash with small portions of washing liquid
c. Ionic salts containing common ion must be added to the washing liquid to increase the solubility of the precipitate
d. Gelatinous precipitates require more washing than crystalline precipitates

Answer 12

c. Ionic salts containing common ion must be added to the washing liquid to increase the solubility of the precipitate

Question 13

15. What is the extent of ionization of the second proton of 0.5 M H_{2}SO_{4} at 25 deg *C
    a. 1%
    b. 2%
    c. 4%
    d. 8%

Answer 13

b. 2%

Question 14

It is the expressed as the volume of a solution chemically equivalent to a mass of a solid reagent
a. titer
b. aliquot
c, molarity
d. ppm

Answer 14

a. titer

Question 15

What weight of Mn ore should be taken so that the percentage of MnO2 (86.94) in the ore would be twice the mass of Mn_{3}O_{4} (228.82) precipitate obtained in milligram?
a. 19.0 mg
c. 57.0 mg
d. 76.0 mg
b. 38.0 mg

Answer 15

c. 57.0 mg

Question 16

Process by which an agglomerated colloid return to its dispersed state during washing due to leaching of electrolyte responsible for its coagulation
b. coagulation
c. agglomeration
a. nucleation
d. peptization

Answer 16

d. peptization

Question 17

Which of the following aqueous solutions of the same concentration will have the largest pH value at 25 deg * C ?
a. NH3
b. KCI
c. NH_{4}Cl
d. NaF

Answer 17

a. NH3

Question 18

Which of the following solutions at 25 deg * C will have the lowest pH value?
a. ,SO, ( K lambda2 of H_{2}SO_{4} = 1.2 * 10 ^ - 2)
b. 5.2 * 10 ^ 4 M HCI
c. 0.05 M NaCN (K. of HCN-6.2 x 10-10)
d. 0.01 MNH,C1 (KA N * H_{4} ^ 2 = 5.6 * 10 ^ - 16 )

Answer 18

d. 0.01 MNH,C1 (KA N * H_{4} ^ 2 = 5.6 * 10 ^ - 16 )

Question 18

Which of the following acid-base pairs will result in the formation of a buffer solution when titration is done before the equivalence point?
a. NaOH and HCI
b. KOH-HNO,
c. NH-HBr
d. all of these

Answer 18

c. NH-HBr

Question 19

What volume of 0.1025 M HCI must be added to 15.64 mL of 0.0956 M NH, to produce a solution of pH =9.00?
a. 5.3 ml.
b. 7.3 mL
c. 9.3 ml
d. 11.3 ml

Answer 19

c. 9.3 ml

Question 20

Which of the following statements is not correct?
a. The buffer capacity is always a positive number
b. The larger the buffer capacity, the more resistant the solution is to pH change is maximum over a pH range of p*K_{b} + 1
c. In general, alkaline buffering capacity
d. The acid buffering capacity is maximum at pH equal to pK

Answer 20

c. In general, alkaline buffering capacity

Question 21

Approximately how many grams of NH4Cl (53.45) should be dissolved in a liter of 0.125 F NH, to reduce the concentration of hydroxide ions to one-thousandth of its original value?
a. 79.1 g
b. 62.5 g
c. 11.7 g
d. CHPO4

Answer 21

a. 79.1 g

Question 22

The conjugate base of H_{2}P * O_{4} ^ - 1 is
a. HPO 2
b. P * O_{4} ^ - 3
d. 7.91 g
d. P_{2}O_{5}

Answer 22

d. P_{2}*O_{5}

Question 23

In the standardization of an acid solution with primary standard sodium carbonate, why is it necessary to boil the solution before completing the titration?
a. to eliminate the reaction product, carbon dioxide and carbonic acid
b. to destroy the buffering action of the resulting solution due to the presence of carbonic acid and unreacted hydrogen carbonate
c. to achieve a sharper endpoint with methyl red indicator due to the large decrease in pH
d. all of the these

Answer 23

d. all of the these

Question 24

Calculate the molarity of NaOH solution if 12.25 mL. was used to titrate 0.2615 gram of primary standard KHP. a. 0.1045 b. 0.1354 c. 0.2509 d. 0.1697

Answer 24

a. 0.1045

Question 25

What is the best basis for choosing the right indicator for a given acid-base titration from among the following? a. type of acid b. type of base c. pH at equivalence point d. molarity of the acid or base

Answer 25

c. pH at equivalence point

Question 26

In standardizing a solution of NaOH against 1.431 grams of KHPuses 35.50 mL of the alkali and has to run back with 8.25 mL of acid ( 1mL = 10.75 mg NaOH). What is the molarity of the NaOH solution? a. 0.2118 M b. 0.2044 M c. 0,7831 M d. 0.2598 M

Answer 26

d. 0.2598 M

Question 27

In the titration of a weak acid with a strong base, which of the following is the best indicator to be used? a. bromocresol green b. methyl orange c. methyl red d. phenolphthalein

Answer 27

d. phenolphthalein

Question 28

A 0.2055-g sample of calcite (impure CaCO₃) is treated with 27.18 ml of 0.0712 HCI and the excess is found to require 5.44 ml of 0.0869 N NaOH for back titration Calculate the percentage purity of calcite in terms of % wt/wt CaCO, (100) a. 17.8% b. 35.6% c. 53.4% d. 71.2%

Answer 28

b. 35.6%

Question 29

Process of determining the nitrogen content of organic materials by mixing the sample with powdered copper (11) oxide and ignited to a combustion tube giving C*O_{2} H₂O, N, and small amounts of nitrogen oxides. a. Kjeldahl Method b. Dumas Method c. Winkler Method d. Wij's Method

Answer 29

b. Dumas Method

Question 30

What is the % wt NaOH for the sample containing a mixture of NaOH - N * a_{2}*C*O_{3} ? d. 11.13% a. 1.82% b. 5.22% c. 10.64%

Answer 30

a. 1.82%

Question 31

In the analysis of nitrogen using Kjeldahl Method, which of the following is added to decompose organic matrices present in the sample? a. H_{2}*S*O_{4} b. HgO C. K_{2}*S*O_{4} d. H2O2

Answer 31

d. H_{2}*O_{2}

Question 31

Which of the following is not used as primary standard for the standardization of alkali solutions? a. HgO b. H_{2}*C_{2}*O_{4} c. HSO,NH, d. C_{6}*H_{5} COOH

Answer 31

a. HgO

Question 31

A 7.279-gram sample of meat was analyzed for its nitrogen content using Kjeldahl Method. Upon digestion, the ammonia liberated was collected in 250 mL of 0.855 M H_{3}*B*O_{30} The resulting solution was titrated with 37.25 mL of 0.3122 M HCI using indicator. Determine the % protein in the sample using 6.25 as factor for meat products. a. 13.98% b. 2.24% c. 19.69% d. 3.14%

Answer 31

a. 13.98%

Question 32

A 1.500-gram sample of impure aluminum chloride was dissolved in water and treated with mL of 0.1000 M AgNO, using K_{2}*Cr*O_{4} as indicator. Express the analysis in \%AICl 1 (133.33). a. 40.28% b. 13.43% c. 4.48% d. 27.36%

Answer 32

b. 13.43%

Question 33

Which of the following is not a correct analytical method-titrant pair? a. Mohr-AgNO, b. Fajans-AgNO, c. Volhard - AgNO, d. Liebig - AgNO,

Answer 33

c. Volhard - AgNO,

Question 34

A mixture of LiBr (86.845) and BaBr, (297.22) weighing 800 mg is treated with 50.00 ml. of 0.1879 M AgNO, and the excess is found to require 8.76 mL of 0.3179 M KSCN for back titration, using ferric alum as indicator. What is the percentage of BaBr, in the sample? a. 67.95% b. 32.05% c. 35.62% d. 64.38%

Answer 34

a. 67.95%

Question 35

A 500 mg sample containing NaCN required 23.50 ml. of 0.1255 M. AgNO, to obtain a permanent faint turbidity Express the result of this analysis as % CN a. 15.34% b. 23.01% c. 17.25% d. 30,67%

Answer 35

d. 30,67%

Question 36

In Volhard Method, why is it necessary to carry out titration in acidic solution? a. To prevent precipitation of iron as hydrated oxide b. To prevent formation of AgSCN precipitate c. To prevent reduction of halide d. To prevent precipitation of silver as hydrated as hydrated oxide

Answer 36

a. To prevent precipitation of iron as hydrated oxide

Question 37

A 750.25-milligram alloy of nickel was dissolved and treated to remove the impurities. Its ammoniacal solution was treated with 50 mL of 0.1075 M KCN and the excess cyanide required 2.25 mL of 0.00925 M AgNO, Determine % Ni (58.69) in the alloy. a. 20.86% b. 37.69% c. 10.53% d. 41.72%

Answer 37

c. 10.53%

Question 38

Which the following ions best titrated with EDTA at minimum pH less than 7? a. C * a ^ - 2 b. S * r ^ - 2 c. M * g ^ - 2 d. F * e ^ - 3

Answer 38

d. F * e ^ - 3

Question 39

An EDTA solution was prepared by dissolving the disodium salt in IL of water. It was standardized using 0.5063 gram of primary standard CaCO, and consumed 28.50 mL of the solution. The standard solution was used to determine the hardness of a 21 sample of mineral water, which required 35.57 mL of the EDTA solution. Express the analysis in terms of ppm CaCO. a. 89 ppm b. 316 ppm c. 158 ppm d. 269 ppm

Answer 39

b. 316 ppm

Question 40

Which of the following statements is true? a. Multidentate chelating agents form weaker complexes with metal ions b. All metals can be determined with high precision and accuracy using chelometric titration c. Eriochrome black T gives a sharp endpoint for the titration of calcium d. Ca-EDTA complex is more stable than Mg-EDTA complex

Answer 40

d. Ca-EDTA complex is more stable than Mg-EDTA complex

Question 41

The 300 mg sample of impure Na₂SO₄ (142.04) was dissolved in sufficient water and the sulfate was precipitated by the addition of 35.00 mL of 0.1022 M BaCl₂. The precipitate was removed by filtration and the remaining BaCl, consumed 6.79 mL of 0.2467 M EDTA for titration to the Calmagite endpoint. Calculate the purity of the sample. a. 80% b. 85% c. 90% d. 95%

Answer 41

c. 90%

Question 42

Commonly, the analyte in a sample is present in two different oxidation states. Pre-reduction is then necessary before titration. One of the metallic reductors is zinc soaked in a dilute solution of mercuric chloride. This reductor is known as a. Walden reductor b. Devarda Alloy c. Lindlars catalyst d. Jones redactor

Answer 42

d. Jones redactor

Question 43

lambda*tpH = 7 and a pressure of 1 bar, the potential for the half reaction, 2H^ + (aq) +2e^ -H 2( is a. 0 V b. -0.414 V c. -0.828 V d.-1.255 V

Answer 43

b. -0.414 V

Question 44

Which of the following is false about iodine as an oxidizing agent in titration? a. Standard iodine solutions have low smaller electrode potential b. Sensitive and reversible indicators are readily available c. Iodine is very soluble in water and losses are minimal d. The solution lacks stability and requires regular standardization

Answer 44

c. Iodine is very soluble in water and losses are minimal

Question 45

All of the following is used as oxidant in redox titrations except a. KMnO b. Cerium (IV) c. K2Cr2O7 d. KI

Answer 45

c. K2Cr2O7

Question 46

What is the molarity of a KMnO, solution standardized against 1.356 gram N*a_{2}*C_{2}*O_{4} (134 * k/(mol)) requiring 25.1 mL of the solution in acidic medium? a. 0.161 M b. 0.403 M c. 1.008 M d. 0.856 M

Answer 46

a. 0.161 M

Question 47

A sample of iron ore weighing 385.6 mg was dissolved in acid and passed through a Jones reductor. The resulting solution 52.36 mL of 0.01436 M K_{2}*C*r_{2}*O for titration to the diphenylamine sulfonic acid endpoint. Calculate % F*e_{3}*O_{4} (231.55 * 8/(mol)) in the ore sample. a. 15.05% b. 45.15% c. 90.30% d. 67.98%

Answer 47

c. 90.30%

Question 48

A sample of pyrolusite weighing 0.2400 gram was treated with excess KI. The iodine liberated required 46.24 mL of 0.1105 M N*a_{2}*S_{2}*O_{3} solution. Calculate % MnO, (86.94) in the sample. a. 46.27% b. 30.85% c. 92.54% d. 76.12%

Answer 48

c. 92.54%

Question 49

Which of the following metal is not reduced by Walden reductor? a. Cr b. Fe c. Cu d. V

Answer 49

a. Cr

Question 50

A 10.00 gram sample of cooked-ham was pureed with 200 mL of water, filtered and the resulting solution containing dissolved potassium nitrite was acidified. This solution was treated with 25.00 mL of 0.00514 M KMnO, and was back titrated with 14.97 mL of 0.01678 M FeSO4. Calculate the amount of nitrite (46.01) in ppm. a. 450 b. 900 c. 1350 d. 1800

Answer 50

b. 900

Question 51

Which of the following is used as a pre-oxidant? a. sodium bismuthate b. ammonium peroxydisulfate c. sodium peroxide d. all of these

Answer 51

d. all of these

Question 52

A 100 mL water sample was analyzed by Winkler Method. If 7.52 mL of 0.0124 M was used for titration, determine the ppm of O_{2} in the water sample. a. 2.8 N*a_{2}*S_{2}*O_{3} b. 3.5 c. 6.4 d. 7.5

Answer 52

d. 7.5

Question 53

A 500 mg sample of a solution containing cobalt (58.93) and nickel (58.69) was dissolved and diluted to 500 mL. A 25 mL aliquot was treated with a complexing agent to produce a colored complex and the volume was adjusted to 50 mL. The following data were obtained for the simultaneous determination in a 1.00-cm cell: Calculate the concentration of Co in the solution in ppm a. 1172 ppm b. 1940 ppm c. 2142 ppm d. 2343 ppm

Answer 53

d. 2343 ppm