1
Q
Sampling type that eliminates questions of bias in selection
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2
Q
When aqueous and nonaqueous liquids are combined, they usually form an immiscible mixture, such as oil and water. A ________ helps in separating the liquids into two samples.
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3
Q
Mixtures of liquids and solids are usually separated prior analysis by
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4
Q
Pre-treatment of solid samples prior analysis.
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5
Q
In the decomposition and dissolution of solids during sample preparation, which of the following is expensive and often the last resort?
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6
Q
Reliability of the results decreases with a decrease in the level or concentration of the:
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7
Q
Properties of nitric acid making it the preferred acid for digesting samples for the analysis of metals
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8
Q
Primary sample preparation method for organics
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9
Q
Possible sources of contamination during sample preparation include:
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10
Q
Containers that should not be used for dry ashing because the elevated temperatures exceed the melting point of these materials
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11
Q
The size of the sample taken for analysis depends on the concentration of the
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12
Q
Equipment commonly used to homogenize the contents of an open beaker.
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13
Q
The maximum holding time for acid preserved samples that will be subjected to determination of metals is
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14
Q
A fraction of the sample actually used in the final laboratory analysis.
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15
Q
A change in the analytical signal caused by anything in the sample other than analyte.
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16
Q
Medium containing analyte.
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17
Q
The total error of an analytical result is the sum of
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18
Q
The holding time for samples for metal determination preserved using nitric acid, 4 mL of dilute 3:1 is
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19
Q
When samples cannot be dried because they decompose at the temperatures necessary to drive off the water, the samples can be analyzed as
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20
Q
Organic components in solid samples are extracted from the matrix by continuously washing the solid with a volatile solvent in a specialized piece of glassware
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21
Q
In liquid-liquid extraction, it is often necessary to determine which liquid is aqueous and which liquid is nonaqueous. To test the liquids, add a drop of water to the top layer. If the drop dissolves in the top layer, the top layer is
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22
Q
It is important to discard containers that are scratched or abraded on their interior surfaces. The internal surface area of a container, whether used for sample preparation or storage, may cause loss of
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23
Q
Process by which a sample population is reduced in size to an amount of homogeneous material that can be conveniently handled in the lab in which the composition is representative of the population.
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24
Q
As a general rule, the error in sampling and the sample preparation portion of an analytical procedure is considerably higher than that in the
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25
Locating the adulterated portion of the lot for sampling is an example of
26
Homogenization during sample preparation can be achieved using mechanical devices (e.g., grinders, mixers, slicers, blenders), enzymatic methods (e.g., proteases, cellulases, lipases) or chemical methods (e.g., strong acids, strong bases, detergents).
27
Glass container is not suitable for
28
To increase/decrease analyte concentration, pre-concentration is needed for almost all trace analysis, ________ is used for the analysis of highly contaminated samples so the concentration falls within the calibration range.
29
Partitioning of analytes between water phase and organic phase
30
Calculate the equivalent weight and normality for a solution of 6.0 M H3PO4 given the following reactions: (a) H3PO4(aq) + 3OH–(aq) PO43–(aq) + 3H2O(l) (b) H3PO4(aq) + 2NH3(aq) HPO42–(aq) + 2NH4+(aq) (c) H3PO4(aq) + F–(aq) H2PO4–(aq) + HF(aq)
31
What is the molality of solution made by dissolving 25 g of NaCl into 2.0 Liter of water. Assume the density of water d = 1.0 g/mL (= kg/L).
32
The amounts of all constituents in the samples were determined
33
Implies that the constituent determined was present in high concentration
34
Quantitative chemical analysis of weighing a sample, usually of a separated and dried precipitate.
35
A chemical grade of highest purity and meets or exceeds purity standards set by American Chemical Society
36
Which of the following is a primary standard for use in standardizing bases?
37
How would you prepare 500.0 mL of 0.2500 M NaOH solution starting from a concentration of 1.000 M?
38
A student performs five titrations and obtains a mean result of 0.110 M, with a standard deviation of 0.001 M. If the actual concentration of the titrated solution is 0.100 M, which of the following is true about the titration results?
39
How many grams of Sodium Persulfate (Na2S2O8) required to prepare a 1 L solution of Sodium Persulfate with concentration of 10% (w/v). This solution is widely used as an oxidizing reagent for Total Organic Carbon analyzer (TOC).
40
A solution has been prepared by transferring 60 mL from Ortho-phosphoric acid 85% (v/v) H3PO4 and diluting it to 1.0 L, what is the concentration of the new solution.
41
A student has got three stock standard solutions of 3 different elements, zinc (Zn) 2000 ppm, cadmium (Cd) 1500 ppm and lead (Pb) 1000 ppm. A student took 10 mL from each solution and transferred it to a 200 mL volumetric flask then completed to total volume with solvent. What is the final concentration of each element in the diluted mix solution?
42
Bidirectional harpoons or double arrows (⇆) should be used to indicate ________ reactions
43
A few ways in which solution composition can be described are as follows.
44
The substance which does the dissolving and must be greater than 50% of the solution.
45
Naphthalene (C10H8) is one of the aromatic hydrocarbons measured by GC-MS. If molecular weight of naphthalene is 128.6 g/mol; how many milligrams are required to prepare 100 mL of 2,000 ppb stock standard solution of naphthalene from powder Naphthalene (purity of 91.5% w/w)?
46
Used to measure volumes approximately, typically with errors of several percent except for one.
47
Nitrate (NO3–) anion solution prepared by dissolving 3.0 g of KNO3 in 250 mL of water. What is the concentration of Nitrate ion, expressing the concentration in Molarity and ppm.
48
The number of formula mass of any solute dissolved in 1 liter of solution
49
The method of standardization can be used if a _______________ reacts quantitatively with the reagent needed in the standard solution.
50
You have a stock solution of 15.8 M HNO3. How many mL of this solution should you dilute using only a graduated pipette to make 100.0 mL of 0.250 M HNO3?
51
HCl cannot be considered to be a primary standard because of its gaseous form at room temperature, but its solutions may be standardized against anhydrous ______.
52
When making a solution from a solid reagent, if necessary, dry the solid reagent on a clean, oven dried, watch glass at 105 ºC for 2 hours and cool it in a desiccator.
53
Requirements of primary standards.
54
Blank samples are prepared so that you have a measure of the amount that needs always to be added to or subtracted from the end point to achieve the ________ point.
55
Which of the following hastens the rate of solution?
56
A solution is _______ if more solute can dissolve in it.
57
The normality of a solution is always _______ the molarity.
58
Which of the following concentration units is independent of temperature?
59
A solution contains 34.0% by mass HClO4 (100.45). It has a density of 1.242 g/ml. The molarity of the solution is
60
The normality of the solution is
61
The molality of the solution is
62
The mole fraction of the solute is
63
The mole fraction of the solvent is
64
The recommended procedure for preparing a very dilute solution is not to weigh out a very small mass or measuring a very small volume of a stock solution. Instead it is done by a series of dilutions. A sample of 0.8214 g of KMnO4 (158.04) was dissolved in water and made up to the volume in a 500-mL volumetric flask. A 2.000-mL sample of this solution was transferred to a 1000-mL volumetric flask and diluted to the mark with water. Next, 10.00 mL of the diluted solution was transferred to a 250-mL flask and diluted to the mark with water. What is the concentration (in molarity) of the final solution?
65
Calculate the mass of KMnO4 needed to directly prepare the final solution
66
Which is not a volumetric glassware?
67
Ambient laboratory conditions are not the same as standard conditions, therefore the volumes dispensed in volumetric glassware are often not the same as the manufacturer's specifications, but within some acceptable limits determined by the manufacturer. This slight variation in volume will cause a _________ error that is based on volume-volume or mass-volume concentrations.
68
Filters that can be heated and used in gravimetric analysis.
69
Objects cannot be weighed when hot or warm. But if you were to take a sample out and wait for it to cool it would pick up moisture like that so put it in ________.
70
Weighing to constant weight means a weighing difference of ±0.1 mg using a calibrated analytical balance.
71
The following are common desiccants except for _______
72
During ignition for ashing, muffle furnaces that go up to 1100°C are used primarily for this and ________ is needed to contain the sample.
73
In making standard solutions, ______ are used for measuring liquid with high accuracy.
74
Used for distillation or heating of liquids, allows uniform heating.
75
Most popular burettes are 10 mL, 25 mL and 50 mL types. Which has the highest resolution?
76
Used for vacuum filtration using filter paper.
77
The nominal volume of water (or mercury) contained, or delivered by an article of volumetric glassware, at its reference temperature.
78
In verification of laboratory glassware, ________ is usually measured in terms of the tolerance, which is the uncertainty in a measurement made with the glassware. Class A volumetric glassware has a lower tolerance than Class B.
79
Glass apparatus that are generally received with calibration certificates from suppliers.
80
The following will cause drift errors in an analytical balance except:
81
It is a document that provides useful information on the chemical hazards, advice on safe handling, use and storage, and the emergency measures to be followed in case of an accident. It usually contains 16 headings.
82
In operating a UV-Vis spectrophotometer, the following shall be done, except for:
83
In maintenance and storage of pH meters, which of the following procedure shall not be done?
84
In using fume hoods, the following shall be done, except for:
85
Which of the following does not require a minimum of annual third party calibration?
86
In starting-up laboratory operations the following should be observed except ________.
87
The following must be avoided in using the analytical balance except ______________.
88
Which of the following must be performed before using the analytical balance?
89
Sealable enclosures containing desiccants used to protect chemicals which are hygroscopic or which react with water from humidity.
90
To determine the specific gravity of a liquid, which of the following glassware should be used?
91
Preparation of highly toxic and volatile compounds should be carried out in an efficient _____________.
92
Which of the following shall not be followed when boiling a solution in a hot plate?
93
How many grams of sodium chloride are required to prepare 250 mL of a solution of 1 M sodium chloride?
94
In recording laboratory results, the following shall be done, except:
95
In determination of chlorides using argentometric titration, what indicator shall be used?
96
In sample acceptance, which of the following shall be checked?
97
Method of passing the sample through a metal or plastic mesh of a uniform cross-sectional area to separate particles into uniform sizes.
98
Method that involves mechanical cutting of sample into smaller parts
99
This refers to a single sample or measurement taken at a specific time or over as short a period as feasible.
100
A sample comprising two or more increments selected to represent the material being analyzed.
101
Which of the following parameters shall be analysed immediately after collection?
102
Method by which the sample is processed to be uniform in texture and consistency by breaking down into smaller parts and blending
103
Type of subsampling in which the sample is mixed to form a pile and then spread out to a flattened disk. The disk is then divided into 4 parts and one of the opposite pair is used as the laboratory sample.
104
Sample preparation that involves the process of decomposition of organic matter
105
The following are good sampling practices except:
106
Process of which the sample is heated to the boiling point of the solvent and volatile analytes are concentrated in the vapour phase, condensed and collected.
107
Which of the following is not an ideal place to install the analytical balance?
108
A series of reference standards solutions that have known and accurate pH values at different temperatures used for pH meter calibration.
109
A property of a wave which is described as the distance between a point on one wave and the same point on the next wave.
110
Which of the following should not be done in using a cuvette?
111
It is the measure of hydrogen ion activity in aqueous solutions.
112
Component of error which, in the course of a number of analyses of the same measurand, remains constant or varies in a predictable way.
113
Component of error which arises from unpredictable variations of influence quantities.
114
Series of analytical measurements used to assess the quality of the analytical data
115
Determine the actual volume contained in a 50.0 mL volumetric flask given the following data: Mass of water: 50.1227 g, Density of water at 25˚C: 0.99707 g/mL
116
Light sensitive samples should be collected in a/an __________ container.
117
A solution consisting of petroleum ether, n-hexane and ethyl acetate is subjected to fractional distillation. What compound will be recovered first given the following boiling points? Dichloromethane = 39.6°C, n-hexane = 68°C, Xylene = 140°C.
118
The dilution of concentrated acid is an exothermic process. It is best to:
119
How many grams of sodium hydroxide is needed to prepare 500 mL of 0.5 N sodium hydroxide?
120
The scientific notation of 0.0078 µg/mL of compound A is?
121
To prepare a 1L of 1000 ppm solution of calcium chloride, how many grams of calcium chloride dihydrate should be weighed?
122
Choose the formula to be used when you have to prepare a 0.3 N solution of NaOH form 5 N NaOH.
123
It is a pure dry solid substance of known chemical composition used in the direct standardization of solution.
124
Which of the following is a cause of contamination during the sample preparation?
125
The following are different types of sample preservation except:
126
It is the closeness of the agreement between the result of a measured value and a true value.
127
Which of the following is not a sample size reduction technique for solid samples?
128
Sample preparation technique used prior to instrumental analysis of metals.
129
Detects contamination from reagents, sample handling, and the entire measurement process
130
Organic compounds in aqueous sample A will be extracted using liquid-liquid extraction. Which of the following is the most appropriate solvent to use?
131
Sample preparation method in which electromechanically driven rod or vibrating base is used to break particles down mechanically into smaller units; can be performed in wet or dry state
132
Sample preparation in which the sample is allowed to settle by leaving it undisturbed in a vessel.
133
Preservation technique for water samples intended for metals determination that cannot be analyzed immediately
134
All of the following are measures of precision except:
135
Given the following data set , determine if any of the values can be rejected.
136
A characteristic of random errors is that
137
Which of the following types of errors can be traced to a defect in the measuring instrument?
138
Systematic errors lead to a lack of
139
Calculate the 95% confidence interval for the following numbers: 116.0, 97.9, 114.2, 106.8 and 108.3. t=2.78
140
What test is used to determine whether a suspected outlier in a series of determinations can be rejected or included in the determination of the mean?
141
use of dessicator
142
use of volumetric flask
143
use of pipette
144
use of beaker
145
use of graduated cylinder
CT: Anachem
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