A standard solution of an organic chromophore has a concentration of and yields an…

CHEMISTRY · Single correct · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures

Problem

A standard solution of an organic chromophore has a concentration of 4.00×10−5 M4.00\times10^{-5}\,\text{M} and yields an absorbance of 0.512±0.0050.512\pm0.005. An unknown sample of the same species gives an absorbance of 0.393±0.0040.393\pm0.004 under identical conditions. Assuming the only significant uncertainties are those in the absorbance readings, which of the following is the best estimate of the concentration of the unknown, including its propagated uncertainty? (a) (3.1 ± 0.6)×10−5 M(3.1\,\pm\,0.6)\times10^{-5}\,\text{M} (b) (2.9 ± 0.06)×10−5 M(2.9\,\pm\,0.06)\times10^{-5}\,\text{M} (c) (3.1 ± 0.06)×10−5 M(3.1\,\pm\,0.06)\times10^{-5}\,\text{M} (d) (5.2 ± 0.1)×10−5 M(5.2\,\pm\,0.1)\times10^{-5}\,\text{M}

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