We show that quantitative molecular absorption spectrometry is based on Beer's law, which can be written as log T = εbcX, where T is the transmittance of a solution of an analyte X, b is the thickness of the absorbing solution, cX is the molar concentration of X, and ε is an experimentally determined constant. By measuring a series of standard solutions of X, εb was found to have a value of 2505 ± 12 M⁻¹, where the number in parentheses is the absolute standard deviation. An unknown solution of X was measured in a cell identical to the one used to determine εb. The replicate results were T = 0.273, 0.276, 0.268, and 0.274. Calculate (a) the molar concentration of the analyte cX; (b) the absolute standard deviation of cX; and (c) the coefficient of variation of cX.
