ChTLE 2024 Analytical Chemistry Pre-Board Exam (3/4)

Sample preparation depends on:

A. the nature of the sample

B. the analyte to be determined and their concentrations/amounts

C. the desired determination precision and accuracy.

D. all of the above

D.

An acid that turns paper towel black, a very dense syrupy liquid that gets especially hot when mixed with water is:

A. Sulfuric Acid

B. Nitric Acid

C. Hydrochloric Acid

D. Perchloric Acid

A.

PEL stands for:

A. personal exposure limit

B. permissible exposure limit

C. permissible exposure time length

D. none of the above

B.

What does SPE stand for?

A. Sample preparation evaluation

B. Solid phase extraction

C. Solid phase evaporation

D. Sample processing experiment

B.

The label CORROSIVE on a chemical container indicates:

A. that the material is an oxidant

B. that contact destroys living tissue as well as equipment

C. that the material can degrade rapidly upon exposure to air

D. All of the above

B.

When diluting an acid with water:

A. do it quickly, so that a cool fountain of toxic material is ejected from the flask

B. do not stir the flask, because it might break

C. always add acid to water, not water to acid, so that the heat of reaction can be controlled

D. None of the above

C.

When operating a fire extinguisher, remember the mnemonic PASS. PASS represents the steps used to properly operate the extinguisher and it stands for which of the following?

A. Pin, Aim, See, Swing

B Pull, Access, Seize, Sweep

C. Plan, Access, Squeeze, Swing

D. Pull, Aim, Squeeze, Sweep

D.

A "Class-A" fire extinguisher can be used to treat fires involving _____ as fuel sources.

A. ordinary combustibles (woods, plastics, etc.)

B. flammable or combustible liquids

C. electrical equipment

D. combustible metals

A.

Given the unbalanced equation below, how many grams of carbon dioxide will be produced from one mole of glucose and six moles of oxygen?

C6H12O6+O2→CO2+H2O

A. 12

B. 4

C. 6

D. 10

C.

A blank used to test the integrity of reagents used in the laboratory. For example, a new batch of solvent might be tested for impurities, or distilled or deionized water would be tested to

ensure that it is pure.

A. reagent blank

B. field blank

C. surrogate

D. instrument blank

A.

Which sampling term is incorrectly defined?

A. laboratory sample - smaller, homogeneous sample taken from the bulk and has the same composition as the bulk

B. lot - the total material from which samples are taken

C. aliquot - small portions of the bulk sample taken for individual analysis

D. sample preparation - the series of steps that convert a representative bulk sample into a form suitable for analysis

C.

The liquid solution containing the analyte is passed through a cartridge containing a solid sorbent.

A. Liquid-liquid extraction

B. solid phase extraction

C. purge-and-trap

D. none of the above

B.

An example of a nonpolar organic solvent that is often used for extracting analytes from aqueous solutions.

A. hexane

B. acetic acid

C. n-butanol

D. water

A.

The analyte in a sample may be too concentrated or too dilute for the chosen method. If it is too concentrated, a dilution with a compatible solvent may be performed. The dilution should be performed with _______________glassware and with good analytical technique so that the dilution factor is known and accuracy is not diminished.

A. graduated glassware

B. graduated plastic wares

C. volumetric glassware

D. nesslers tubes

C.

A ___________is a substance used in a chemical reaction in an analytical laboratory because of its specific applicability to a given system or procedure.

A. reagent

B. sample

C. media

D. test kits

A.

Choose the sample that would be best dissolved by HNO3.

A. NaCl

B. Iron ore

C. Copper metal

D. Aluminum Oxide

C.

From the following list, choose those samples that would be best dissolved by HCl.

A. NaCl

B. Iron ore

C. Gold metal

D. Aluminum Oxide

B.

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)

A. (a) 18 N, (b) 12 N and (c) 6N

B. (a) 12 N, (b) 18 N and (c) 6N

C. (a) 6 N, (b) 12 N and (c) 18N

D. (a) 16 N, (b) 12 N and (c) 3N

A.

What is the molality of solution made by dissolve 25 g of NaCl in to 2.0 Liter of water. Assume the density of water d = 1.0 g/mL (= kg/L).

A. 0.210 m

B. 0.250 m

C. 0.211 m

D. 0.214 m

D.

The amounts of all constituents in the samples were determined.

A. Complete (or ultimate) analysis

B. Partial analysis

C. Elemental analysis

D. All of the above

A.

Implies that the constituent determined was present in high concentration.

A. Trace analysis

B. Macro analysis

C. Elemental analysis

D. All of the above

B.

Quantitative chemical analysis of weighing a sample, usually of a separated and dried precipitate.

A. Titrimetric analysis

B. Volumetric analysis

C. Gravimetric analysis

D. Elemental analysis

C.

A chemical grade of highest purity and meets or exceeds purity standards set by American Chemical Society.

A. Technical grade

B. Laboratory grade

C. Pure or practical grade

D. ACS grade

D.

Which of the following is a primary standard for use in standardizing bases?

A. Ammonium hydroxide

B. Sulfuric acid

C. Acetic acid

D. Potassium hydrogen phthalate

D.

How would you prepare 500.0 mL of 0.2500 M NaOH solution starting from a

concentration of 1.000 M?

A. Transfer 125 mL from initial solution (1.000 M) and complete with solvent to 500.0 mL.

B. Transfer 121 mL from initial solution (1.000 M) and complete with solvent to 500.0 mL.

C. Transfer 122 mL from initial solution (1.000 M) and complete with solvent to 500.0 mL.

D. Transfer 112 mL from initial solution (1.000 M) and complete with solvent to 500.0 mL.

A.

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?

A. Accurate but not precise

B. Precise but not accurate

C. Both accurate and precise

D. Neither accurate nor precise

B.

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 oxidizing reagent for Total Organic Carbon analyzer (TOC).

A. 100 g of Sodium Persulfate

B. 101 g of Sodium Persulfate

C. 102 g of Sodium Persulfate

D. 99 g of Sodium Persulfate

A.

A solution has been prepared by transfer 60 mL from Ortho-phosphoric acid 85 % (v/v) H3PO4 and dilute to 1.0 L, what is the concentration of the new solution.

A. 10.10%

B. 9.25%

C. 12.2%

D. 5.10%

D.

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 transfers it to 200 mL volumetric flask then completed to total volume with solvent. What is the final concentration of each element in the diluted mix solution?

A. 50 ppm Zinc, 32 ppm Cd, 25 ppm Pb

B. 100 ppm Zinc, 75 ppm Cd, 50 ppm Pb

C. 75 ppm Zinc, 75 ppm Cd, 50 ppm Pb

D. 100 ppm Zinc, 25 ppm Cd, 25 ppm Pb

B.

Bidirectional harpoons or double arrows (⇆) should be used to indicate ________ reactions.

A. one sided

B. resonance

C. dynamic

D. reversible

D.

In the preparation of 1 liter of 1.0 N acid from 35% Hydrochloric Acid, what weight of the impure acid should be taken, assuming standardization in the recommended manner?

A. 101.29

B. 113.29

C. 111.29

D. 124.89

A.**

A few ways in which solution composition can be described are as follows.

A. Molarity

B. Normality

C. Molality

D. All of the above

D.

The substance which does the dissolving and must be greater than 50% of the solution.

A. Solvent

B. solute

C. mixture

D. solution

A.

Naphthalene (C10H8) is one of 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)?

A. 2.18

B. 2.1858

C. 2.186

D. 2.1859

B.**

A student has to measure out 9.40 mL of a liquid and selects a 100 mL graduated cylinder. To improve the accuracy of the measurement, it would be most effective to:

A. take the average of multiple measurements using the graduated cylinder.

B. measure the liquid using a 25 mL graduated cylinder instead.

C. estimate the measurement obtained from the graduated cylinder to an additional

significant figure.

D. measure the liquid using a 10 mL graduated pipette instead.

D.

Nitrate (NO3-) anion solution prepared by dissolving 3.0 g of KNO3 in 250 mL of water. What is the concentration of Nitrate ion? Express the concentration in Molarity and ppm.

A. 0.1187 M, 7359.05 ppm

B. 0.1190 M, 7349.05 ppm

C. 0.1107 M, 7459.00 ppm

D. 0.1120 M, 7400.00 ppm

A.

The number of formula mass of any solute dissolved in 1 liter of solution.

A. Formality

B. normality

C. molality

D. molarity

A.

A 0.217 g sample of HgO (molar mass = 217 g) reacts with excess iodide ions according to the reaction. Titration of the resulting solution requires how many mL of 0.10 M HCl to reach

equivalence point?

HgO + 4 I− + H2O → HgI4 2- + 2 OH−

A. 1.0 mL B. 10 mL C. 20 mL D. 50 mL

C.**

If the theoretical yield for a reaction was 156 grams and I actually made 122 grams of the product, what is my percent yield?

A. 78.2%

B. 128%

C. 19.0%

D. none of these

A.

The method of standardization can be used if a _______________ reacts quantitatively with the reagent needed in the standard solution.

A. primary standard

B. secondary standard

C. working standards

D. intermediate solution

A.

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 .250 M HNO3?

A. 1.58

B. 1.582

C. 1.50

D. 1.583

A.

If 56.0 g of Li reacts with 56.0 g of N2, 93.63 grams of Li3N can be produced. How many grams of Nitrogen remains? What is the limiting reactant?

A. 19.3 g; Nitrogen

B. 18.3 g N; Lithium

C. 20.3 g N; none

D. 18.39 ; Lithium

B.

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 ______.

A. NaSO4

B. NaHCO3

C. Na2CO3

D. All of the above

C.

When making a solution from a solid reagent, if necessary, dry the solid reagent on a clean, oven dried, watch glass at ____ for 2 hours and cool it in a desiccator.

A. 121 deg-C

B. 105 deg-C

C. 80 deg-C

D. 118 deg-C

B.

Requirements of a primary standards.

A. High Purity, 99.9% or better

B. Stability in air

C. Absence of hydrate water

D. All of the above

D.

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.

A. titration error

B. equivalence

C. accuracy

D. precision

B.

A specially manufactured analytical reagent of exceptional purity for standardizing solutions and preparing reference standards.

A. working standard

B. secondary standard

C. primary standard

D. internal quality control standard

C.

A reagent that meets the standards of purity established by the manufacturer. The certificate of analysis is on the label.

A. certified reagent

B. secondary standard

C. primary standard

D. internal quality control standard

A.

Chemicals of reasonable purity for applications that have no official standard for purity.

A. Analyzed Reagent

B. ACS grade

C. Technical Grade

D. Practical grade

C.

Solvents of suitable purity for use in spectrophotometric procedures. A certificate of analysis is on the label.

A. Spectro grade

B. HPLC grade

C. Technical Grade

D. Practical grade

A.