A high equivalent weight is desirable for compounds used as primary standards because

Which of the following could be a random error in analytical measurements?

Which is an example of a systematic error that may occur while weighing a solid on a balance?

Two laboratories performed parallel tests for the determination of Pb in an air particulate sample. To compare whether the means of each set of measurements are different or not, what is the appropriate test to use?

Four determinations of a bromide solution in a sample yielded the following values: 43.28%, 43. 19%, 43.62%, and 43.24%. The Q-test value for four measurements at the 90% confidence level is 0.76. What is the best average report for these results?

A sample of iron ore from the Bureau of Standards was analyzed and the following results were obtained: mean= 10.53%, s= 0.11 for a total of 10 measurements. The Bureau's value for this sample is 10.61% iron. How do these results differ at 95% confidence level (t = 2.26)?

When it is best to use external standards for calibration of instrument response? I. When the analysis is significantly affected by matrix effect. Il. When there are no interference effects from matrix components in the analyte solution. Ill. When analyzing a large number of samples with uniform composition.

When performing calculations for standard additions, which of the following must be TRUE?

Analyte in an unknown gave a signal of 10.0 mV. When 1.00 mL of 0.0500 M standard was added to 100.0 mL of unknown, the signal increased to 14.0 mV. Find the concentration of the original unknown.

The table below shows a chromatographic data for the analysis of benzene using ethylbenzene as the internal standard. What is the concentration benzene in the sample?

A standard solution of barium hydroxide is 0.250 M. What volume of 0.200 M nitric acid would be required to neutralize 10.0 mL of the barium hydroxide solution?

A NaOH solution is to be standardized by titrating it against a known mass of potassium hydrogen phthalate (KHP). Which of the following instances wil give a molarity that is too low?

The molar mass of a solid carboxylic acid is determined by titrating a known mass of the acid with a standardized solution of NaOH to a phenolphthalein endpoint. Which errors will lead to a molar mass that is smaller than the actual molar mass? I. Some of the acid is spilled when being transferred into the titration flask. Il. The endpoint is recorded when the solution is dark red in color rather than light pink.

The zinc in a 0.7457-g sample of foot powder was titrated with 22.57 mL of 0.01639 M EDTA. Calculate the wt% of Zn in this sample.

Which of the following is the indicator used in Mohr titration?

This indicator is used for titrations involving iodine. It forms a dark blue complex with iodine.

The amount of ascorbic acid in a vitamin C tablet is determined by titration with a solution of iodine in aqueous potassium iodide. A small amount of starch is added to the vitamin C solution before the titration. What is the function of starch?

lodometric titration would be least suitable for which determination?

A pH meter is an example of which type of membrane electrode?

A 1.00 g sample of a silver-containing ore is dissolved ni dilute nitric acid. The solution is neutralized and then selectively electrolyzed to deposit the silver metal, requiring 670s of 0.10A current. What is the wt% of Ag in the ore?

Voltammetric methods are based on measuring ___________ as a function of the ____________ applied to a small electrode.

The differential pulse polarogram of 3.00 mL of solution containing tetracycline in 0.1 M acetate, pH 4, gives a maximum current of 152 nA at half-wave potential of -1.05 V(vs. SCE). When 0.500 mL containing 2.65 ppm of tetracycline was added, current increased to 206 nA. How much tetracycline is in the original solution?

Which technique(s) is(are) based on size to separate the analyte and interferent? I. Dialysis II. Extraction III. Centrifugation IV. Size-exclusion chromatography

Which separation technique(s) is(are) based on partitioning between phases? I. Extraction II. Distillation III. Sublimation IV. Chromatography

Which technique separates charged particles using electric field?

If 99.1% of a compound dissolved in 25.0 mL of water is extracted into 25.0 mL of organic solvent, then the distribution coefficient for the compound between the organic solvent and water is ________.

In a simple extraction of an organic compound from water with an organic solvent, the relative distribution ratio is 50. Determine the amount of solute that will remain in 200 mL of water if after extraction there are 10.0 mg of solute in the 100-mL volume of organic phase.

Solute A has a partition coefficient of 4 between diethyl ether and water. If 100 mL of a 0.1 M aqueous solution of A is extracted twice with 100 mL of diethyl ether, what is the resulting concentration of A in the aqueous layer?

Assume that in extraction from water into toluene, analyte A has the distribution ratio of 10. A 20-mL portion of an aqueous solution of A is extracted with toluene. Which of the following procedures will result in the most efficient removal of A from the aqueous phase into toluene?

The elution power of a mobile phase is determined by

Band broadening in column chromatography is a result of which of the following?

A chromatographic peak is determined to have a retention time and baseline peak width of 3.756 and 0.412 min, respectively. The number of theoretical plates for the peak is

An advantage of HPLC over GC for the separation and measurement of high molecular weight compounds is that

Reversed-phase chromatography refers to which of the following?

Which of the following has the correct order of elution from an HPLC column containing a reversed-phase packing?

In anion-exchange chromatography,

Hexanoic acid and 1-aminohexane, adjusted to pH 3 with HCl, were passed through a cation-exchange column loaded with HCl at pH 3. Which of the following will be retained?

Which light source should be used in the wavelength range of 340 to 1000 nm?

Which of the following is the correct order in which light passes through a UV-Vis spectrophotometer?

What is the purpose of a monochromator?

A student gets fingerprints on a cuvette before using it. What wil be the effect on the absorbance and reported concentration?

In Beer's law, molar absorptivity multiplied by path length represents ______ of the calibration curve.

Why must solutions with high concentrations be diluted prior to analysis via Beer's Law?

A photometer gave a reading of 837 mV with a blank in the light path and 333 mV when the blank was replaced by an absorbing solution. What are the transmittance and absorbance of the solution?

The true absorbance of a sample is 1.500, but 0.50% stray light reaches the detector. Find the apparent absorbance of the sample.

Widely used continuous atomization method in AAS. It is also the most reproducible of all liquid-sample introduction methods that have been developed for AAS to date.

A hollow cathode tube lamp is necessary in AAS because

Which of the following is the correct sequence of during the atomization process ni AAS?

The plasma in ICP-AES consists of

In AAS, if the sample concentration is too high to allow accurate analysis linearity response range, which of the following can be done that can help bring the absorbance in into the optimum range?

The iron content of a municipal water supply was determined by an atomic absorption procedure. The absorbance of the water sample, after a five-fold dilution, was 0.646 at 248 nm. Astandard solution, prepared by dissolving 0.1483 g of pure iron wire in acid, diluting to 250.0 mL, and then making 100-fold dilution, had an absorbance of 0.813. What is the Fe content (ppm) of the water sample?

A soft ionization method in mass spectrometry that is typically applied to biomolecules that involves a laser striking a solid matrix to ionize the analyte without fragmentation or decomposition.

The presence of a functional group in a compound can be established by

Coprecipitates (inclusions, occlusions, and surface adsorbates) are a common problem in gravimetric analysis, but can be controlled by which of the following?

Type of coprecipitation in which a compound is trapped within a pocket formed during rapid crystal growth.

Occlusion and ________ are confined to crystalline precipitates. _______ occurs when cry stals lie close together during growth. Several crystals grow together and in doing so trap a portion of the solution in a tiny pocket.

Excess silver nitrate is added to 0.2000 g of impure magnesium chloride. Silver chloride is carefully collected, dried and weighed and found to weigh 0.2800 g. What is the %magnesium chloride in the original sample?

A 5.0-g sample of calcium nitrate contaminated with silica is found to contain 1.0 g calcium. What is the mass percent purity of calcium nitrate in the sample?

Which thermal analysis method measures weight loss as a function of temperature in a controlled environment?

Which thermal analysis method calculates flow by measuring how much heat it takes increase the temperature of a sample compared to a reference material.

Which of the following is(are) the application(s) of DTA? I. For studying and characterizing polymers. II. For the generation of phase diagrams and the study of phase transitions. IlI. Provides a simple and accurate way of determining the melting, boiling, and decomposition points of organic compounds.

This analysis allows discrete sampling of elements as it disregards the chemical form of a sample and focuses solely on its nucleus. Moreover, it is one of the standard techniques in the analysis of art and archaeological samples.

Which of the following is(are) the advantage(s) of NAA? I. high sensitivity Il. minimal sample preparation IlI. can be nondestructive so NAA can applied to the analysis of art objects, coins, forensic samples, and archaeological specimens

The concentration of Ni in a new alloy is determined by a NAA. A 0.500-g sample of the alloy and a 1.000-g sample of a standard alloy that is 5.93% w/w Ni are irradiated with neutrons in a nuclear reactor. When irradiation is complete, the sample and the standard are allowed to cool and their gamma ray activities measured. Given that the activity is 1020 cpm for the sample and 3540 cpm for the standard, determine the wt% of Ni in the alloy.

It involves the addition of known amounts of isotopically-enriched substance to the sample being analyzed.

When a 25.00 mL volumetric flask weighing 20.340 g is filled partially with metal shot the mass is 119.691 g. The flask is then filled to the 25.00 mL mark with methanol (0. 791 g/cu.cm) and has a total mass of 130.410 g. What is the density of the metal?

A student determines the number of moles of water in a hydrated metal oxide by weighing a clean, dry crucible and lid while the crucible is empty, then reweighing the crucible and lid with a sample of the hydrate, heating the crucible and lid with a Bunsen burner and then reweighing the crucible and lid with the sample after cooling to room temperature. Which error will result in too high a value for the amount of water of hydration?