ChTLE 2024 Analytical Chemistry Pre-Board Exam (2/4)

A solution is prepared by dissolving 464 g of NaOH (MM=40) in water and then diluting to one liter. The density of the resulting solution is 1.37 g/ml.

The molarity of the solution is:

A. 33.87 M

B. 12.80 M

C. 11.6 M

D. 50.33 M

C.

A solution is prepared by dissolving 464 g of NaOH (MM=40) in water and then diluting to one liter. The density of the resulting solution is 1.37 g/ml.

The molality of the solution is:

A. 33.87 m

B. 12.80 m

C. 11.6 m

D. 50.33 m

B.

A solution is prepared by dissolving 464 g of NaOH (MM=40) in water and then diluting to one liter. The density of the resulting solution is 1.37 g/ml.

The mole fraction of NaOH is:

A. 11.6

B. 0.187

C. 0.813

D. 12.80

B.

A solution is prepared by dissolving 464 g of NaOH (MM=40) in water and then diluting to one liter. The density of the resulting solution is 1.37 g/ml.

The mole fraction of H2O is:

A.0.187

B. 0.813

C. 33.87

D. 11.6

B.

234 g of sodium chloride is reacted with sulfuric acid to produce hydrogen chloride gas and sodium sulfate.

Which of the following statement is not true:

A. The balanced chemical equation is 2NaCl + H2SO4 -----> 2 HCl + Na2SO4.

B. According to the balanced equation, 2 moles of NaCl produce 2 moles of HCl.

C. From 234 g of NaCl, 146 g of HCl is formed.

D. 2 moles of sodium sulfate are formed for every mole of NaCl reacted.

D.

Which of the following statements about acids and bases is not true:

A. Water undergoes autoionization.

B. Strong acids and strong bases are ionized completely in dilute aqueous solutions.

C. The strength of an acid or a base is measured by the extent of its ionization in solution.

D. Strong acids form strong conjugate bases.

D.

Which statement about Arrhenius acids is FALSE?

A. Their water solutions are called aqueous acids.

B. They are molecular compounds with ionizable hydrogen atoms.

C. Their pure aqueous solutions are electrolytes.

D. They increase the concentration of hydroxide ions in aqueous solution.

D.

Strong bases are:

A. strong electrolytes.

B. nonelectrolytes

C. weak electrolytes

D. also strong acids

A.

59.What is the pH of a 1 x 10^-4 M HCl solution?

A. 4

B. 8

C. 6

D. 10

A.

60.What is the pH of a 1 x 10^-5 M KOH solution?

A. 3

B. 9

C. 5

D. 11

B.

What is the molarity of an HCl solution if 50.0 mL is neutralized in a titration by 40.0 mL of 0.400 M NaOH?

A. 0.200 M

B. 0.320 M

C. 0.280 M

D. 0.500 M

B.

Which are the correct products for these reactants HCl + NaOH?

A. HOH + ClNa

B. H3O + NaCl2

C. NaCl + H2O

D. NaOH + Cl

C.

The symbol for Silver element is:

A. S

B. Si

C. Sr

D. Ag

D.

Which of the following substance is a salt:

A. HCl

B. NaOH

C. NaBr

D. None

C.

Which of the following compounds contains an ionic bond?

A.NH3

B. H2O

C. CaO

D. H2

C.

Systematic errors may arise from avoidable sources, except:

A. contamination, reagent impurities,

B. wrongly calibrated instruments, instrumental mal- functions,

C. poor sampling techniques, errors in calculations

D. electronic noise in the circuit of an electrical instrument

D.

Systematic errors primarily influence a measurement's _________.

A. Accuracy

B. Precision

C. Standard deviation

D. Mean

A.

An improperly calibrated thermometer may give accurate readings within a certain temperature range, but become inaccurate at higher or lower temperature.

A. Random error

B. Gross error

C. Systematic error

D. Analyst error

C.

An error caused by not setting an instrument to zero prior to its use is called an ______ error.

A. Offset error

B. Random error

C. Gross error

D. Systematic error

A.

In the decomposition and dissolution of solids during sample preparation, which of the following is expensive and often the last resort?

A. Acid treatment using oxidation

B. Fusion technique

C. Dissolution using ultrasound and appropriate solvent

D. Simple dissolution

B.

Reliability of the results decreases with a decrease in the level or concentration of the:

A. matrix

B. analyte

C. reactant

D. product

B.

Properties of nitric acid making it the preferred acid for digesting samples for the analysis of metals:

A. acts as a strong acid

B. as an oxidizing agent

C. does not form insoluble compounds with metals/nonmetals

D. All of the above

D.

Primary sample preparation method for organics.

A. Sonication

B. Acid-digestion

C. Extraction

D. All of the above

C.

Possible sources of contamination during sample preparation include:

A. Reagents (tracers)

B. Glassware/equipment

C. Cross-contamination between high- and low-activity samples

D. All of the above

D.

Containers that should not be used for dry ashing because the elevated temperatures exceed the melting point of these materials.

A. zirconium

B. platinum

C. Glass and plastic

D. porcelain

C.

Determinate errors are also called ____________.

A. Bias

B. Random error

C. Gross error

D. Systematic error

D.

An error that is known to have occurred but was unavoidable.

A. Bias

B. Random error

C. Gross error

D. Systematic error

A.

The maximum holding time for acid preserved samples that will be subjected to determination of metals is:

A. 3 months

B. 1 week

C. 6 months

D. 48 hours

C.

Refers to the repeatability of a measurement.

A. Accuracy

B. Precision

C. Specificity

D. Mean

B.

A change in the analytical signal caused by anything in the sample other than analyte.

A. matrix effect

B. interference

C. absorbance

D. transmittance

A.

Medium containing analyte.

A. reactant

B. matrix

C. solute

D. reference material

B.

The total error of an analytical result is the sum of:

A. sampling

B. sample preparation

C. analytical errors

D. All of the above

D.

The holding time for samples for metal determination preserved using nitric acid, 4 mL of dilute 3:1 is:

A. 28 days

B. 2 weeks

C. 3 days

D. 1 year

A.

The following numerical results were obtained in a given laboratory experiment: 0.09376, 0.09358, 0.09385, and 0.09369. Calculate the relative parts per thousand standard deviation.

A. 1.2

B. 1.1

C. 1.3

D. 1.4

A.

The following are analytical strategy steps except for one.

A. obtain the sample

B. prepare the sample

C. carry out the analysis method

D. releasing of results

D.

A student determines the weight of an object on an analytical balance to be 12.2843 g. The actual weight, unknown to the student or to anyone else, is 12.2845 g. What kind of error is this?

A. Determinate

B. indeterminate

C. gross

D. none of the above

B.

A given analytical test was performed five times. The results of the analysis are represented by the following values: 6.738, 6.738, 6.737, 6.739, and 6.738%. The results are:

A. Accurate

B. precise

C. not precise

D. not precise and not accurate

B.

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.

A. Selection

B. monitoring

C. sampling

D. segregation

C.

A sample that has all the characteristics in exactly the same proportion as the bulk sample where it came from:

A. representative sample

B. test sample

C. gross sample

D. subsample

A.

Locating the adulterated portion of the lot for sampling is an example of:

A. random sampling

B. selective sampling

C. composite sampling

D. stratified sampling

B.

In gravimetric analysis:

A. the mass of a solution is used to calculate the quantity of the original analyte.

B. the mass of a product is used to calculate the quantity of the original analyte.

C. the mass of a product is used to calculate the quantity of the impurity.

D. none of the above

B.

Glass container is not suitable for:

A. inorganic trace analyses

B. oil and grease determination

C. microbiological analyses

D. all of the above

A.

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.

A. centrifugation

B. separation

C. dilution

D. all of the above

C.

Chemical derivatization is used to increase or decrease volatility for ____________ analysis.

A. AAS

B. GC and HPLC

C. PCR

D. X-ray Diffraction

B.

Acid digestion via hot-plate digestion or microwave-assisted is one way of sample preparation in the analysis of:

A. Total metal

B. Bioactive compounds

C. Alcohols

D. Sugars

A.

GFAA (Graphite Furnace Atomic Absorption) do not use HCl since Cl- interferes. Diluted ______ acid is used.

A. Phosphoric Acid

B. Acetic acid

C. Nitric Acid

D. Sulfuric Acid

C.

Partitioning of analytes between water phase and organic phase.

A. Liquid-liquid extraction

B. Solid phase extraction

C. Ultrasonic extraction

D. Pressured Fluid Extraction (PFE)

A.

The original undivided sample that was taken directly from the bulk system being characterized.

A. bulk sample

B. test sample

C. subsample

D. laboratory sample

A.

A primary sample is the same as:

A. Subsample

B. test sample

C. bulk sample

D. laboratory sample

C.

If a water sample is to be analyzed for trace levels of metals, glass container for sampling and storage is inappropriate due to the following reasons except for one.

A. it could leach trace level metals and contaminate the sample

B. it can absorb some analytes

C. very impure as compared to quartz, PTFE, PP

D. losses of elements due to adsorption are very high

B.