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Chem Tech > Analytical Chemistry > Flashcards

Analytical Chemistry Flashcards

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1
Q

The elution power of a mobile phase is determined by

A

the nature of the sample components, its overall polarity, the polarity of the stationary phase

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2
Q

Which of the following statements about columns containing more theoretical plates is TRUE?

A

Columns containing more theoretical plates are better suited to separate a complex mixture

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3
Q

The height equivalent of a theoretical plate (HETP) has all of the following characteristics EXCEPT

A

This quantity times the column length is equal to the number of theoretical plates in the column

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4
Q

All of the following are common carrier gases from gas chromatography EXCEPT

A

Oxygen

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5
Q

The following are properties of an open tubular or capillary column EXCEPT

A

Poor resolution can be obtained.

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6
Q

An air sample is subjected to gas chromatography for the analysis of Freon-11 (CCIF). The detector that is most suitable for this analysis is

A

ECD

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7
Q

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

A

The preparation of volatile derivatives is not necessary in HPLC.

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8
Q

Reversed-phasechromatography refers to which of the following?

A

A nonpolar stationary phase and a polar mobile phase

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9
Q

Which of the following has the correct order of elution (first to last) from an HPLC column containing a reversed-phase packing?

A

acetamide, acetone, dichloroethane

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10
Q

The following will cause the drift errors in an analytical balance EXCEPT

A

Temperature of the balance and the sample to be weighed is the same.

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11
Q

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 so it should be placed in a/an/at

A

desiccator

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12
Q

It is the nominal volume of water (or mercury) contained, or delivered by an article of volumetric glassware, at its reference temperature.

A

Capacity

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13
Q

A student is tasked to measure 12 mL of a liquid as precisely as possible. Which measuring device should be selected for this task?

A

25 mL graduated cylinder

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14
Q

A student needs to transfer his precipitant from the beaker to the filter paper. Which of the following would be the best procedure in order to ensure a quantitative transfer of the precipitate?

A

Most of the supernatant liquid decanted first, then bulk of the precipitate is transferred through a stirring rod. The beaker is washed several times with small volumes of wash solution.

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15
Q

To determine the density of a liquid, which of the following should be used?

A

pycnometer

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16
Q

Which technique is recommended for determining the odor of an unknown liquid in the laboratory?

A

Use a hand to fan some of the vapor from the test tube to the rose and inhale.

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17
Q

The size of the sample taken for analysis depends on the/concentration of the

A

equipment to be used, analyte, specific chemical tests

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18
Q

Which of the following can cause ERRORS during the sample preparation?

I. Loss of sample during weighing or dissolution.

II. Contamination by impurities in reagents and in the environment.

III. Changes in mass due to varying humidity and temperature.

IV. Obtaining nonhomogeneous sample from the bulk.

A

I, II, III, and IV

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19
Q

In an experiment to determine the percentage of water in a solid hydrate by heating, what is the best indication that all the water has been removed?

A

Successive weighing’s give the same mass.

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20
Q

What is the [H3O+] of a 0.100 M solution of HCN at 25oC? Ka (HCN) = 4.0 x 10−10

A

6.32 x 10−6 M

21
Q

When exposure to hazards cannot be engineered completely out of normal operations, this supplementary method of control can be used.

A

use of PPE

22
Q

A researcher working in the lab where hazardous liquid chemicals are present. Which of the following is NOT considered appropriate PPE for this situation?

A

Wire mesh glove

23
Q

The reactant which is present in the smallest stoichiometric amount and which limits the amount of product that can be formed in a reaction is

A

the limiting reagent

24
Q

A polar solute usually dissolves in a polar solvent and a nonpolar solute usually dissolves in a nonpolar solvent.

A

the “like dissolves like” rule

25
Q

A solution is _______ if more solute can dissolve in it.

A

unsaturated

26
Q

The normality of a solution is always ________ the molarity.

A

greater than or equal to

27
Q

Which of the following concentration units is independent of temperature?

A

molality

28
Q

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

A

8.40

29
Q

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. 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 were transferred to a 250-ml flask and diluted to the mark with water. What is the concentration (in molarity) of the final solution?

A

8.316 x 10‒7 M

30
Q

In this column type, the retention is governed by the interaction of the polar parts of the stationary phase and solute.

A

normal phase

31
Q

The HPLC column type in which molecules are separated according to size.

A

size exclusion

32
Q

We have a 5.43 x 10−4 M solution of HNO3 at 25℃. What is the [OH−] in this solution?

A

3.67 x 10−6 M

33
Q

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. 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 were transferred to a 250-ml flask and diluted to the mark with water. Calculate the mass of KMnO4 needed to directly prepare the final solution.

A

3.28 x 10‒5 g

34
Q

Weighing to constant weight means a weighing difference of ______ using a calibrated analytical balance.

A

±0.1mg

35
Q

The following are common desiccants except for __________

A

Ammonium Acetate

36
Q

In chromatography,_________ is carried out on glass plates or strips of plastic or metal coated on one side with a thin layer of adsorbent.

A

Thin Layer Chromatography

37
Q

Conductivity could be determined using the distance between the electrodes and their surface area using Ohm’s law but, for accuracy, a calibration is employed using _________of well-known conductivity.

A

electrolytes

38
Q

At 510 nm, the iron orthophenanthroline complex has a molar absorptivity of 1.2 x 104. What is the concentration of iron (in ppm) in a solution which gives an absorbance of 0.002 in a 1.00-cm path length cell?

A

9.3 x 10-3 ppm

39
Q

The electrical conductivity of water is directly related to the concentration of dissolved ionized solids in the water or

A

Total Dissolved Solids

40
Q

The light source used in the visible range to 340-1000 nm.

A

tungsten

41
Q

The % T of a solution in a 2.00 cm cell is 50. Calculate the %T of this solution in a 1.0 cm cell path length.

A

71

42
Q

An air sampling canister was evacuated by the local fire dep’t and brought to the environmental lab for analysis. It was said that the sample was taken very near the site where a rusty 55- gal drum was found by some children. A reported unpleasant smell near the site was reported. Results of gravimetric analysis of the gas in the canister: C – 40%, H- 6.7%, O – 53.33%. What is the liquid in the drum?

A

CH2O

43
Q

When NH4Cl hydrolyzes, the resulting solution is

A

acidic

44
Q

What is the pH of a 5.82 x 10−3 M solution of NaOH at 25oC?

A

11.76

45
Q

The total volume of a average adult lungs when expanded is about 6 liters. Calculate the pressure of oxygen inhaled if 0.05 mole of oxygen is needed to fully fill a pair of average adult lungs at a normal body temperature of 370C.

A

0.212 atm

46
Q

Which of the following is NOT suitable safety attire when handling large volume of corrosive liquid?

A

General safety glasses

47
Q

Ambient laboratory conditions are not the same to 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 are based on volume-volume or mass-volume concentrations.

A

systematic

48
Q

Glass cuvettes are typically for use in the wavelength range of visible light, whereas fused quartz tends to be used for ______ applications.

A

UV/visible

49
Q

The pH of a 0.20 M NH3 solution is Kb (NH3) = 1.8 x 10‒5

A

11.28

Chem Tech (2 decks)

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