Question 1

What mass of a solid sample containing 2.5% analyte particles and 97.5% solvent particles must be taken to give a standard deviation of 2% of the number of analyte particles,if the average particle volume is 2.54 nL and the sample has an average density of 1.548 g/mL?

Accepted Answer

0.3834 g sample

Question 2

Sample preparation of a laboratory sample can involve all of the following,except: A)laboratory samples that do not dissolve under mild conditions may require acid digestion or fusion. B)organic material may be destroyed by combustion or wet ashing. C)solids are typically dried at 110 ^oC at atmospheric pressure to remove absorbed water prior to analysis. D)a portion of a course solid laboratory sample should be ground into a fine powder for analysis. E)temperature-sensitive samples may be stored in an environment to achieve a constant,reproducible moisture level.

Accepted Answer

D

Question 3

A mixture contains 2.5% KBr and 97.5% inert particles.What is the relative standard deviation for KBr is 50 000 particles are taken?

Accepted Answer

2.79% for KBr

Question 4

For random errors,the overall variance,  ,is calculated from the analytical variance,  ,and the sampling variance,  .Which is the correct equation for calculating the overall variance?
A) 
B) 
C) 
D) 
E)

Accepted Answer

The answer of For random errors,the overall variance,  ,is...

Question 5

____________________ dissolves substances that will not dissolve in acid in a hot,molten inorganic____________________.
A)Smelting;solvent
B)Fusion;flux
C)Smelting;flux
D)Fusion;solvent
E)None of these choices is correct.

Accepted Answer

Fusion involves melting substances, and a flux is used to dissolve impurities that won't dissolve in acid, facilitating their removal from the desired material.

Question 6

Sample storage is an important aspect of sample preparation.Which is NOT true for sample storage?
A)Glass should not be used with trace analysis of ions and proteins in solution.
B)Analytes may react with the container.
C)A stored sample may change with time.
D)New plastic containers do not require washing before use.
E)A stored sample may react with air.

Accepted Answer

New plastic containers may still have residues from production that can affect the sample, thus requiring washing before use. The other options are true for sample storage.  Glass should not be used with trace analysis of ions and proteins in solution as it may cause contamination. Analytes may react with the container, a stored sample may change with time, and a stored sample may react with air, which can all impact the accuracy and reproducibility of the sample analysis.

Question 7

________________________________________uses a small volume of chromatographic stationary phase or molecularly imprinted polymer to isolate analytes from the sample matrix to simply analysis.
A)Solid-phase extraction
B)Polymer extraction
C)Chromatographic extraction
D)Antigen extraction
E)Solvent-free extraction

Accepted Answer

Solid-phase extraction (SPE) is a technique that uses a small volume of chromatographic stationary phase to isolate analytes from the sample matrix. It is commonly used in sample preparation to simplify analysis by removing interfering substances and concentrating the analytes of interest. Polymer extraction and solvent-free extraction are not specific techniques, and chromoatographic extraction may refer to a variety of different chromatography types, making A the most specific and likely choice. Antigen extraction is also not a relevant technique for sample preparation.

Question 8

Which samplng 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
E)bulk sample - representative sample taken from the lot for analysis or archiving

Accepted Answer

The answer of Which samplng term is incorrectly defined?
A)laboratory sample...

Question 9

All of the following are used to grind solids into a fine powder,except:
A)mortar and pestle.
B)Wig-L-Bug
C)Shatterbox laboratory mill.
D)ball mill.
E)vortexer.

Accepted Answer

Vortexers are not used for grinding solids into a fine powder, but rather for mixing liquids or suspensions. The other options listed are all commonly used for grinding solids.

Question 10

What mass will give a sampling standard deviation of 3.5% for a sampling constant of 40.9?

Accepted Answer

The answer of What mass will give a sampling standard...

Question 11

To calculate the number of required replicates for analysis the equation is used.Which statement is NOT true for the equation and calculation? A)t = the Student's t value for n − 1. B)s_s is the sampling standard deviation. C)e is the difference between the sampling standard deviation and the desired sampling standard deviation. D)The initial calculation assumes an infinite n value and the according Student's t value. E)The n value from a calculation dictates the Student's t value used in the next calculation.

Accepted Answer

The answer of To calculate the number of required replicates...

Question 12

Which of the following is INCORRECT for decomposition of organic substances? A)Microwave-induced combustion is a form of dry ashing. B)An example of wet ashing is microwave digestion with acid in a Teflon bomb. C)Wet ashing with perchloric aicd is an extremely hazardous procedure and is best avoided. D)Kjeldahl digestion digests organic material with sulfuric acid for nitrogen analysis. E)The Carius method of wet ashing is performed with fuming H₂SO₄ in a sealed,heavy-walled glass tube at 200 ^oC to 300 ^oC.

Accepted Answer

The Carius method uses fuming HNO3, not fuming H2SO4.

Question 13

Calculate the overall standard deviation if the analytical standard deviation is 6% and the sampling standard deviation is 4%.

Accepted Answer

The answer of Calculate the overall standard deviation if the...

Question 14

A mixture contains 5% NaCl particles and 95% NaBr particles.If 10³ particles are taken,what is the relative standard deviation for NaCl and NaBr? A)13.78% for NaCl 0.73% for NaBr B)186.2% for NaCl 9.80% for NaBr C)95.00% for NaCl 5.00% for NaBr D)54.39% for NaCl 2.86% for NaBr E)6)89% for NaCl 0.36% for NaBr

Accepted Answer

The relative standard deviation (RSD) is calculated using the formula RSD = (standard deviation / mean) * 100%. For NaCl, the mean is 50 particles (5% of 1000), and the standard deviation is the square root of 50, which gives an RSD of approximately 13.78%. For NaBr, the mean is 950 particles (95% of 1000), and the standard deviation is the square root of 950, which gives an RSD of approximately 0.73%.

Question 15

All of the following are true for dissolving inorganic materials in acid,except: A)metals with positive reduction potentials should dissolve in nonoxidizing acids such as HCl,HBr,HF,H₃PO₄,etc. B)volatile species formed by protonation of anions such as carbonate will be lost from hot acids in open vessels. C)volatile metal halides such as SnCl₄ and some metal oxides can be lost from hot acids in open vessels. D)hot hydrofluoric acid dissolves silicates. E)substances that do not dissolve in nonoxidizing acids may dissolve in oxidizing acids such as HNO₃,hot concentrated H₂SO₄,or hot concentrated HClO₄.

Accepted Answer

The statement "metals with positive reduction potentials should dissolve in nonoxidizing acids such as HCl,HBr,HF,HSO4-,etc." is true. The other statements are all true for dissolving inorganic materials in acid.

Question 16

How many replicates must be completed for sampling deviation of 3.5% to achieve a 1% standard deviation?

Accepted Answer

The answer of How many replicates must be completed for...

Question 17

A 4.17 g sample has a 4% sampling standard deviation.What mass sample must be taken to decrease the sampling standard deviation to 2%?
A)8)34 g
B)16.68 g
C)10.43 g
D)4)17 g
E)15.64 g

Accepted Answer

The sampling standard deviation is inversely proportional to the square root of the sample mass. To halve the standard deviation from 4% to 2%, the sample mass must be quadrupled. Quadrupling the initial mass of 4.17 g gives 16.68 g.

Question 18

____________________ is the procedure in which analyte is chemically modified to make the compound easier to detect or separate.
A)Labeling
B)Derivatization
C)Tagging
D)Marking
E)Modification

Accepted Answer

Derivatization is the procedure of chemically modifying the analyte to make the compound easier to detect or separate. This modification can involve adding functional groups or altering the structure of the molecule itself, ultimately improving the sensitivity and selectivity of the analytical method.

Question 19

Which of the following are NOT liquid extraction techniques?
I emulsive liquid-liquid microextraction
II dispersive liquid-liquid microextraction
III solid-supported liquid-liquid extraction
IV supercritical fluid extraction
V solid-liquid microextraction
A)I and II
B)III and V
C)I and IV
D)IV only
E)I and III

Accepted Answer

The answer of Which of the following are NOT liquid...

Quiz 29: Sample Preparation

What mass of a solid sample containing 2.5% analyte particles and 97.5% solvent particles must be taken to give a standard deviation of 2% of the number of analyte particles,if the average particle volume is 2.54 nL and the sample has an average density of 1.548 g/mL?

Sample preparation of a laboratory sample can involve all of the following,except:

A mixture contains 2.5% KBr and 97.5% inert particles.What is the relative standard deviation for KBr is 50 000 particles are taken?

For random errors,the overall variance, ,is calculated from the analytical variance, ,and the sampling variance, .Which is the correct equation for calculating the overall variance?

dissolves substances that will not dissolve in acid in a hot,molten inorganic.

Sample storage is an important aspect of sample preparation.Which is NOT true for sample storage?

________________________________________uses a small volume of chromatographic stationary phase or molecularly imprinted polymer to isolate analytes from the sample matrix to simply analysis.

Which samplng term is incorrectly defined?

All of the following are used to grind solids into a fine powder,except:

What mass will give a sampling standard deviation of 3.5% for a sampling constant of 40.9?

To calculate the number of required replicates for analysis the equation is used.Which statement is NOT true for the equation and calculation?

Which of the following is INCORRECT for decomposition of organic substances?

Calculate the overall standard deviation if the analytical standard deviation is 6% and the sampling standard deviation is 4%.

A mixture contains 5% NaCl particles and 95% NaBr particles.If 10³ particles are taken,what is the relative standard deviation for NaCl and NaBr?

All of the following are true for dissolving inorganic materials in acid,except:

How many replicates must be completed for sampling deviation of 3.5% to achieve a 1% standard deviation?

A 4.17 g sample has a 4% sampling standard deviation.What mass sample must be taken to decrease the sampling standard deviation to 2%?

____________________ is the procedure in which analyte is chemically modified to make the compound easier to detect or separate.

Which of the following are NOT liquid extraction techniques? I emulsive liquid-liquid microextraction II dispersive liquid-liquid microextraction III solid-supported liquid-liquid extraction IV supercritical fluid extraction V solid-liquid microextraction

Quiz 29: Sample Preparation

What mass of a solid sample containing 2.5% analyte particles and 97.5% solvent particles must be taken to give a standard deviation of 2% of the number of analyte particles,if the average particle volume is 2.54 nL and the sample has an average density of 1.548 g/mL?

Sample preparation of a laboratory sample can involve all of the following,except:

A mixture contains 2.5% KBr and 97.5% inert particles.What is the relative standard deviation for KBr is 50 000 particles are taken?

For random errors,the overall variance, ,is calculated from the analytical variance, ,and the sampling variance, .Which is the correct equation for calculating the overall variance?

____________________ dissolves substances that will not dissolve in acid in a hot,molten inorganic____________________.

Sample storage is an important aspect of sample preparation.Which is NOT true for sample storage?

________________________________________uses a small volume of chromatographic stationary phase or molecularly imprinted polymer to isolate analytes from the sample matrix to simply analysis.

Which samplng term is incorrectly defined?

All of the following are used to grind solids into a fine powder,except:

What mass will give a sampling standard deviation of 3.5% for a sampling constant of 40.9?

To calculate the number of required replicates for analysis the equation is used.Which statement is NOT true for the equation and calculation?

Which of the following is INCORRECT for decomposition of organic substances?

Calculate the overall standard deviation if the analytical standard deviation is 6% and the sampling standard deviation is 4%.

A mixture contains 5% NaCl particles and 95% NaBr particles.If 103 particles are taken,what is the relative standard deviation for NaCl and NaBr?

All of the following are true for dissolving inorganic materials in acid,except:

How many replicates must be completed for sampling deviation of 3.5% to achieve a 1% standard deviation?

A 4.17 g sample has a 4% sampling standard deviation.What mass sample must be taken to decrease the sampling standard deviation to 2%?

____________________ is the procedure in which analyte is chemically modified to make the compound easier to detect or separate.

Which of the following are NOT liquid extraction techniques? I emulsive liquid-liquid microextraction II dispersive liquid-liquid microextraction III solid-supported liquid-liquid extraction IV supercritical fluid extraction V solid-liquid microextraction

dissolves substances that will not dissolve in acid in a hot,molten inorganic.

A mixture contains 5% NaCl particles and 95% NaBr particles.If 10³ particles are taken,what is the relative standard deviation for NaCl and NaBr?