ANALYTICAL CHEMISTRY EXAM 1 QUESTIONS AND ANSWERS
1. Define the term precision.: Precision is a measure of the reproducibility of
a result.
2. A systematic error .: can be discovered and corrected.
3. Often the analyst will compare known quantities of analyte to
unknown quantities of the material to be analyzed. This may be
done in one of three ways: use calibration curves; use standard
additions; or use internal stan-dards. The method of standard
additions would be used when: the sample com-position is unknown
or complex and attects the analytical signal
4. A solution is prepared by dissolving 0.6301 g AgNO3 in a 125
mL volumetric flask and diluting to the mark. Calculate the
molarity of the silver nitrate solution.: turn g to mol, then mol to M
0.0297
5. what is included in a method validation?: robustness, linearity, limit of
detection
6. Which of the following is true regarding the matrix effect?: The
matrix ettect may be minimized by using the method of standard additions
1/7
, 7. A chemist is involved in checking the results that were being
obtained in a routine analysis of magnesium. The chemist
decided to purchase a certified standard. This standard would be
purchased from the: NIST, the National Institute of Standards and
Technology
8. What is a blank solution?: a solution containing all reagents and
solvents used but no analyte, measures the response of the impurities or
interfering species, used to determine the limit of detection
9. What volume of concentrated sulfuric acid (94.0%) is required
to prepare 1 liter of a 0.100 M solution if the density is 1.831 g/mL?:
use density to get g/L (1.831g/ml)x(1000mL/1L)x(0.94) = 1721.14g/L
find mol of acid
(1721.14g)/98g =
17.563 mol/L
use MV=MV
5.7 mL
10. One definition of analytical method precision in a GLP
laboratory is ± 5% RSD (relative standard deviation) of the
mean. A quality control (QC) sample was run in replicates of
12.1, 11.9, 11.6, 13.3, 12.8, 12.4, 13.1, and 12.6 ppb. The level
of analytical method precision is acceptable for this group of QC
replicates: True
2/7
1. Define the term precision.: Precision is a measure of the reproducibility of
a result.
2. A systematic error .: can be discovered and corrected.
3. Often the analyst will compare known quantities of analyte to
unknown quantities of the material to be analyzed. This may be
done in one of three ways: use calibration curves; use standard
additions; or use internal stan-dards. The method of standard
additions would be used when: the sample com-position is unknown
or complex and attects the analytical signal
4. A solution is prepared by dissolving 0.6301 g AgNO3 in a 125
mL volumetric flask and diluting to the mark. Calculate the
molarity of the silver nitrate solution.: turn g to mol, then mol to M
0.0297
5. what is included in a method validation?: robustness, linearity, limit of
detection
6. Which of the following is true regarding the matrix effect?: The
matrix ettect may be minimized by using the method of standard additions
1/7
, 7. A chemist is involved in checking the results that were being
obtained in a routine analysis of magnesium. The chemist
decided to purchase a certified standard. This standard would be
purchased from the: NIST, the National Institute of Standards and
Technology
8. What is a blank solution?: a solution containing all reagents and
solvents used but no analyte, measures the response of the impurities or
interfering species, used to determine the limit of detection
9. What volume of concentrated sulfuric acid (94.0%) is required
to prepare 1 liter of a 0.100 M solution if the density is 1.831 g/mL?:
use density to get g/L (1.831g/ml)x(1000mL/1L)x(0.94) = 1721.14g/L
find mol of acid
(1721.14g)/98g =
17.563 mol/L
use MV=MV
5.7 mL
10. One definition of analytical method precision in a GLP
laboratory is ± 5% RSD (relative standard deviation) of the
mean. A quality control (QC) sample was run in replicates of
12.1, 11.9, 11.6, 13.3, 12.8, 12.4, 13.1, and 12.6 ppb. The level
of analytical method precision is acceptable for this group of QC
replicates: True
2/7
