ENCH 213 Lecture Notes - Sodium Chloride, Hygroscopy, Standard Deviation
Document Summary
Sampling considerations: lot: total material, gross or bulk sample: representative of the lot, laboratory sample: with exact same composition as the bulk sample, test portions. Select the one best answer: a a bulk sample is taken from a lot. A bulk sample is taken from a laboratory sample. c a bulk sample is also called a gross sample. d a and c. 2 = variance of the analytical procedure so. Gross sample size depends on: uncertainty between the composition of the gross sample and that of the lot, heterogeneity of the sample, analyte concentration. Particle size distribution: homogeneous solutions of liquids and gases, heterogeneity and particle size at the molecular level, sample size can be relatively small, depends on final use. Establishing and using a sampling constant because sample mass (m) n, and n r: m r. = true population mean e = sought-for uncertainty ss. 2 = sampling variance n = number of replicates.