After OES analysis the concentrations obtained for the solution of Pb2+ from 3 r

Question

After OES analysis the concentrations obtained for the solution of Pb2+ from 3 replicates were 261.1 ppm, 260.9 ppm, 261.8 ppm. Calculate mean and standard deviation for the experimental concentrations. Use the correct number of significant figures for your answer, include units.

Calculate the accuracy of the concentration obtained experimentally (report the value using the correct number of significant figures). If the accepted accuracy is within 1%, is your result within the accepted accuracy?

Explanation / Answer

Data Points, concentration of Pb2+: (X): 261.1 ppm, 260.9 ppm, 261.8 ppm

Mean: (Xav): (261.1 + 260.9 + 261.8)/3 = 261.3 ppm

Standard Deviation :

SQRT( (X-Xav)2/(n-1))

SQRT( (261.6 -261.3)2 + (260.9-261.3)2 + (261.8 -261.3)2 = 0.4725

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