CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
In a research laboratory, an aqueous stock solution of an organic chromophore has an unknown concentration. To determine that concentration, a chemist performs the following steps.
(a) Determine the molar concentration of the diluted solution prepared in step 1. Show all calculations.
(b) Calculate the molar concentration of the original stock solution. Report your answer to the correct number of significant figures.
(c) Using the absorbance uncertainties provided (±0.005 for each reading), estimate the absolute uncertainty in the calculated concentration of the stock solution. Clearly state any assumptions made in your propagation of uncertainty.
(d) The bottle label on the stock solution claims a concentration of 2.0×10−3M. Based on your result and its uncertainty from parts (b) and (c), assess whether the label is accurate. Justify your answer quantitatively.