归东理工大军 Analytical Chemistry 2.2 Types of errors in experimental data 1.Systematic errors ◆Methods Errors in this category arise from undesirable behavior of the reagents and reactions on which an analysis is based. Such sources of nonideality include the slowness of some reactions,the incompleteness of other,the instability of some species
Analytical Chemistry 2025/4/3 11 2.2 Types of errors in experimental data 1. Systematic errors ◆Methods Errors in this category arise from undesirable behavior of the reagents and reactions on which an analysis is based. Such sources of nonideality include the slowness of some reactions, the incompleteness of other, the instability of some species
归东理子大军 Analytical Chemistry the nonspecificity of most reagents,and the possible occurrence of side reactions that interfere with the measurement process. Equipment and materials All measuring devices are sources of determinate error.For example,a voltmeter draws a small current while operating,thereby changing the voltage it is measuring
Analytical Chemistry 2025/4/3 12 the nonspecificity of most reagents, and the possible occurrence of side reactions that interfere with the measurement process. ◆Equipment and materials All measuring devices are sources of determinate error. For example, a voltmeter draws a small current while operating, thereby changing the voltage it is measuring
归东觅子大图 Analytical Chemistry Note that each time the voltmeter is used to measure a particular voltage,the result will be low by the same amount.Thus the error is constant in both magnitude and direction. ◆Personal judgements Many measurements require personal judgement. Examples include estimating the position of a pointer between two scale divisions,the color of a solution at the end point in a titration,or the level of a liquid with respect to a graduation in a pipet of buret
Analytical Chemistry 2025/4/3 13 Note that each time the voltmeter is used to measure a particular voltage, the result will be low by the same amount. Thus the error is constant in both magnitude and direction. ◆Personal judgements Many measurements require personal judgement. Examples include estimating the position of a pointer between two scale divisions, the color of a solution at the end point in a titration, or the level of a liquid with respect to a graduation in a pipet of buret
归东理子大军 Analytical Chemistry Judgements of this type often subject to systematic, unidirectional errors. One of the most common types of judgement errors is an unjustified preference or dislike of certain digit.Number biases are very common,with zero and five being favored digit.It is a difficult bias to overcome,but it can be decreased through self- discipline
Analytical Chemistry 2025/4/3 14 Judgements of this type often subject to systematic, unidirectional errors. One of the most common types of judgement errors is an unjustified preference or dislike of certain digit. Number biases are very common, with zero and five being favored digit. It is a difficult bias to overcome, but it can be decreased through selfdiscipline
归东觅子大图 Analytical Chemistry ◆Mistakes These are errors resulting from carelessness or ignorance and can be decreased by being more careful and informed.Mathematical errors, improper reading of instrument scales and recording,and misrecorded data are the three major sources of such mistakes
Analytical Chemistry 2025/4/3 15 ◆Mistakes These are errors resulting from carelessness or ignorance and can be decreased by being more careful and informed. Mathematical errors, improper reading of instrument scales and recording, and misrecorded data are the three major sources of such mistakes