Quantitative Chemical Analysis Exam Questions Answered Correctly Latest Update 2024 (Graded A+)
Types of errors - Answers systematic error and random error
systemic error - Answers Flow from equipment or the design of experiment; reproducible; determinate
Systemic Error - Answers Can be detected
Types of determinate errors - Answers Instrument error, ph meter, uncalibrated buret,
Ways to detect standard error - Answers Sample analysis, different analytical methods for the same
quantity, blank determinations; using different people
Random error - Answers Arises from the effect of uncontrolled variables in the measurements
What is a characteristic of random error? - Answers Always present; cannot be corrected.
What is the ultimate limitation on the determination of a quantity? - Answers Random error.
What is the probability distribution of random error? - Answers Has an equal chance of being positive or
negative.
Precision - Answers Reproducibility. A can be reproduced but far from accepted value
Accuracy - Answers Closeness to true valie
Classification of Quant. Of Analysis - Answers Can be computed from two measurements; Mass or
volume; measurement of quantity proportional to the amount of analyte
Gravimetric - Answers The mass of analyte or some compound related to the analyte determined
Volumetric - Answers The volume of a solution containing sufficient reagent to react completely with the
analyte measured
Electrochemical - Answers Electrical properties such as potential, current, resistance, and quantity of
charge is measured.
Spectroscopic - Answers Based on measurements of the interaction between electromagnetic radiation
and analyte atoms or molecules
Steps in quantitative Analysis - Answers 1) Select Method
2) Acquire Sample
3) sample preparation
4) Eliminate Interferences
, 5) Measure & calibrate(analyze)
6) Calculate
7) Statistical Evaluation of Results
Significant Figure Rules - Answers The minimum number of digits needed to write a given value in
scientific notation without loss of accuracy
significant figures (sig figs) - Answers Ex.184.6 ; the last SF which is 6 has some associated uncertainty
Significant Figure Rules - Answers The first significant figure is the digit which is known most exactly for
example in 1.846
Rules for determining which digits are significant - Answers 1) all non-zero numbers are significant
2)zeros between nonzero numbers are significant
3)Zero to the right on the nonzero number and to the right of the decimal point are significant
non significant figures - Answers leading zeros
standard deviation formula - Answers Measures how closely the data are clustered about the mean
The smaller the (s) - Answers The more closely the data are clustered about the mean
Q test - Answers Helps to decide whether a datum inconsistent with the rest of the data should be
discarded or included
Q Test - Answers Needs at least 4 measurements
Basics of quality assurance - Answers Raw data; individual values of a measured quantity, such as peak
areas from chromatograph or volume from a buret(1)
Basics of quality Assurance - Answers Treated data; concentrations or amounts found by applying a
calibration procedure to the raw data (2)
Basics of quality Assurance - Answers (3)Results: what we ultimately report, such as mean, standard
deviation, and confidence interval, after applying statistics to treated data
Parts of quality assurance - Answers -Use objectives
-Specifications
-Assessment
Use objectives - Answers Helps prevent misuse of data and results
Types of errors - Answers systematic error and random error
systemic error - Answers Flow from equipment or the design of experiment; reproducible; determinate
Systemic Error - Answers Can be detected
Types of determinate errors - Answers Instrument error, ph meter, uncalibrated buret,
Ways to detect standard error - Answers Sample analysis, different analytical methods for the same
quantity, blank determinations; using different people
Random error - Answers Arises from the effect of uncontrolled variables in the measurements
What is a characteristic of random error? - Answers Always present; cannot be corrected.
What is the ultimate limitation on the determination of a quantity? - Answers Random error.
What is the probability distribution of random error? - Answers Has an equal chance of being positive or
negative.
Precision - Answers Reproducibility. A can be reproduced but far from accepted value
Accuracy - Answers Closeness to true valie
Classification of Quant. Of Analysis - Answers Can be computed from two measurements; Mass or
volume; measurement of quantity proportional to the amount of analyte
Gravimetric - Answers The mass of analyte or some compound related to the analyte determined
Volumetric - Answers The volume of a solution containing sufficient reagent to react completely with the
analyte measured
Electrochemical - Answers Electrical properties such as potential, current, resistance, and quantity of
charge is measured.
Spectroscopic - Answers Based on measurements of the interaction between electromagnetic radiation
and analyte atoms or molecules
Steps in quantitative Analysis - Answers 1) Select Method
2) Acquire Sample
3) sample preparation
4) Eliminate Interferences
, 5) Measure & calibrate(analyze)
6) Calculate
7) Statistical Evaluation of Results
Significant Figure Rules - Answers The minimum number of digits needed to write a given value in
scientific notation without loss of accuracy
significant figures (sig figs) - Answers Ex.184.6 ; the last SF which is 6 has some associated uncertainty
Significant Figure Rules - Answers The first significant figure is the digit which is known most exactly for
example in 1.846
Rules for determining which digits are significant - Answers 1) all non-zero numbers are significant
2)zeros between nonzero numbers are significant
3)Zero to the right on the nonzero number and to the right of the decimal point are significant
non significant figures - Answers leading zeros
standard deviation formula - Answers Measures how closely the data are clustered about the mean
The smaller the (s) - Answers The more closely the data are clustered about the mean
Q test - Answers Helps to decide whether a datum inconsistent with the rest of the data should be
discarded or included
Q Test - Answers Needs at least 4 measurements
Basics of quality assurance - Answers Raw data; individual values of a measured quantity, such as peak
areas from chromatograph or volume from a buret(1)
Basics of quality Assurance - Answers Treated data; concentrations or amounts found by applying a
calibration procedure to the raw data (2)
Basics of quality Assurance - Answers (3)Results: what we ultimately report, such as mean, standard
deviation, and confidence interval, after applying statistics to treated data
Parts of quality assurance - Answers -Use objectives
-Specifications
-Assessment
Use objectives - Answers Helps prevent misuse of data and results
