You wish to measure the iron content of the well water on the new property you are about to buy....
Question:
You wish to measure the iron content of the well water on the new property you are about to buy. You prepare a reference standard {eq}Fe^3+ {/eq} solution with a concentration of {eq}6.89 \times 10^-4 {/eq}M. You treat 10.0 ml. of this reference with {eq}HNO_3 {/eq} and excess KSCN to form a red complex, and dilute the reference to 60.0 mL. The diluted reference is placed in a cell with a 1.00-cm light path. You then take 35.0 mL of the well water, treat with {eq}HNO_3 {/eq} and excess KSCN, and dilute to 100.0 mL. This diluted sample is placed in a variable pathlength cell. The absorbance of the reference and the sample solutions match when the pathlength is 3.87 cm. What is the concentration of iron in the well water?
Beer's Law
Beer's law describes the linear relationship between the absorption of light of a substance and the concentration of the substance. It has the mathematical form
$$A = \epsilon b c $$
where {eq}\epsilon {/eq} is the molar absorptivity of the substance at a given wavelength, b is the pathlength and c is the concentration of the substance.
Answer and Explanation: 1
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View this answerThe concentration of iron in the well water is {eq}8.48 \times 10^{-5}\;M {/eq}
First, the iron in the reference is completely reacted to give the...
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Beer's Law: Absorbance & Concentration
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Chapter 4 / Lesson 5
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Beer's law expresses the relationship between light intensity and the concentration of a substance through a formula. Learn the background of light transmittance and absorbance, and how the equation of Beer's law is used in science.
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