Classify each of the following errors as random or systematic. A tiny crystal of
ID: 896802 • Letter: C
Question
Classify each of the following errors as random or systematic. A tiny crystal of hydrated compound "pops" out of the crucible during heating while determining the percent water in the compound. Some stopcock grease gets on the outside of a crucible just prior to its weighing during the gravimetric sulfate experiment. A pH 8 standard solution is used to calibrate a pH meter to a pH of 7.0. The background current for an electrochemical analyzer fluctuates periodically due to background noise in the electrical lines. A chemical interferent causes the reading for the analyte to be higher than actual during the analysis. Ten different people report slightly different readings of the same volume in a volumetric buret due to visual judgments of the liquid level between the marks.Explanation / Answer
Random Error is an error in measurement which can take place in any direction (positive or negative).
Systematic error is an error which always takes place in either positive or negative direction.
a. As the tiny crystal of the hydrated compound pops out of the crucible the compound along with some water of crystallization is lost. So, the error occured is random.
b. As some stopcock grease gets on the outside of the crucible there will be a positive error in the gravimetric estimation of sulfate. This error is systematic.
c. A solution of pH 8 is used to calibrate a pH meter to a pH of 7.0. So, the pH meter will always show the actual pH-1 result. This error is systematic.
d. As the fluctuation of the background current can take place in any direction this error is a random error.
e. The chemical interferent causes the reading for the analyte to be higher than actual during the analysis causing a positive error. This error is systematic.
f. As ten different people are taking reading of the same burette reading this error is random error and there is a high chance that taking average of all the observation will minimize the magnitude of error.