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WorksheetsAnalytical Chemistry (midterm)
Total questions: 30
Worksheet time: 17mins
1. A type of coprecipitation in which a compound is trapped within a pocket formed rapid crystal growth
surface adsorption
mixed crystal formation
occlusion
mechanical entrapment
A type of coprecipitation in which crystal lie together during growth and doing trap a portion of solution in tiny pocket
mechanical entrapment
occlusion
surface adsorption
mixed crystal formation
What element can be analyzed by the use of dimethylglyoxime in weakly alkaline solution
Nickle
Magnesium
Zinc
Cadmium
Which of the following is not a property of reference materials in titration and in other analytical methods?
Established methods for confirming purity should be available
Absence of hydrate water so that the composition of the solid does not change
Reasonably low molar mass so that relative error associated with weighing with the standard is minimized
Modest cost
1. In an acid base titration using phenolphthalein indicator, the equivalence point is manifested by the appearance of what color?
yellow
blue
orange
purple
1. In the reaction Zn(s) + 2H+(aq) à Zn+2(aq) + H2(g), what is the oxidizing agent?
Zn
Zn2
H+
H2
1. Which of the following is true in this reaction
3NO2- + Cr2O72- + 8H+ à 2Cr+3 + 3NO3- + 4H2O
N of NO2- is reduced, Cr of Cr2O72- is oxidized
N of NO2- oxidized, Cr of Cr2O72- is reduced
O of NO2- oxidized, Cr of Cr2O72- is reduced
Cr+3 is reduced, N of NO2- is oxidized
In the laboratory, a student measured the pH of a 0.599 M aqueous solution of ethylamine, C2H5NH2 (a weak base), to be 12.192. Use the information she obtained to determine the Kb for this base.
2.41 x 10-11
10-1.88
4.15 x 10-4
1.56 x 10-2
When a weak acid is titrated with a strong base, the pH at the equivalence point is ALWAYS
7
<7
>7
<1
1. Which of the following aqueous solutions are good buffer systems?
I. 0.20 M calcium hydroxide + 0.20 M calcium chloride
II. 0.35 M ammonia + 0.32 M ammonium nitrate
III. 0.10 M hypochlorous acid + 0.14 M hydrobromic acid
IV. 0.33 M barium iodide + 0.27 M sodium iodide
V. 0.29 M hydrochloric acid + 0.19 M sodium chloride
II III, and IV
II and V
II
all are good buffers
Which titration curve below represents the titration of a strong base with a strong acid titrant?
a
b
c
none
1. Which titration curve below represents the titration of a weak acid base with a strong base titrant?
a
b
c
none
Which of the following is the INCORRECT statement?
The oxidation number of chlorine atoms in Cl2 is zero.
Oxidation results in an increase in oxidation number.
The oxidizing agent in a redox reaction is reduced.
Reduction is a loss of electrons.
Stable complexes that bind a metal and prevent it from interfering in a determination
EDTA
Masking agent
Adsoprtion indicator
Ligand
Ligands that are bound to metal ion only at one place are called
unilateral
unidentate
bilateral
bidentate
Water soluble chelating agent, non-hydroscopic and very stable sequestering agent
Silver
EDTA
magnesium oxide
sodium hydroxide
Instrumental methods of detecting endpoints suitable for dilute solutions as low as 0.0002M.
Spectrophotometric
Amperometric
potentiometric
high frequency titrator
Type of complexometric titration in which metal that is being analyzed displaced quantitatively from the complex
Direct titration
Back titration
Replacement titration
Indirect titration
Forms a colorless complex with aluminium, yellow complex with iron III, the color of which is almost discharge by adding sodium hydroxide solution and a green manganese complex which oxidizes mordant black II.
Triethanolamine
Tiron
Potassium iodide
Potassium cyanide
Indicator used in complexometric titration for the determination of Cobalt
Mordant black
Thymol blue
sodium alizarine sulfonate
murexide
What is the oxidation number of As in H3AsO4?
-3
+2
+3
+5
Calculate the pH for a buffer solution prepared by mixing 100. mL of 0.10 M HF and 200. mL of 0.10 M KF
2.82
2.96
3.32
3.44
What is the pH at the equivalence point in the titration of 50.0 mL of 0.100 M hydrofluoric acid, HF, (Ka = 7.2 x 10-4) with 0.100 M NaOH?
5.88
6.44
7.92
8.12
Nickel carbonate, NiCO3, has a Ksp of 6.6 x 10-9. What is the molar solubility of nickel carbonate?
3.9 x 10-3 mol/L
4.35 x 10-17 mol/L
6.6 x 10-9 mol/L
8.1 x 10-5 mol/L
A type of titrimetric analysis that required time or current for complete oxidation or reduction of the analyte
(a)
Gravimetric method that is based on the isolation of an insoluble precipitate of known composition
(a)
The concentration of a volumetric solution is determined by titrating it against a carefully measured quantity of a primary or secondary standard or an accurately known volume of another standard solution
(a)
The point in the titration when a physical change occurs that is associated with a condition of a chemical equivalence
(a)
Process where a coagulated colloid reverts to its dispersed state
(a)
A mechanism of precipitation where a small number of ions, atoms, and molecules initially unite, spontaneous and induced
(a)
