4C Pre-Lab Answer Key

4C Pre-Lab Answer Key - ANSWER KEY: EXPERIMENT #4c - Iron...

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1 ANSWER KEY: EXPERIMENT #4c - Iron Analysis PRE-LAB QUESTIONS: 1. (1 point) Let's determine the %T from an Absorbance value of 2.0: %T = (1/10 A ) × 100% = (1/10 2.0 ) × 100% = 1% Transmittance!!! Clearly, a % Transmittance value of 1% is extremely low , meaning that virtually no light escapes the sample (i.e. almost all light is absorbed by the sample). This, in turn, means that, because so little light gets through the sample, errors are very large , and it is difficult to extract meaningful data from the sample. 2. (1 point) Calculate the Absorbance values from the %T: A = log(100%/%T) = log(100%/12.5%) or log(1.0/0.125) = 0.903 or 0.90 A = log(100%/%T) = log(100%/80%) or log(1.0/0.80) = 0.0969 or 0.097 3. (1 point) Beer's Law: A = ε bc ε = A/bc ε = (1.020) / [(2.00 cm)(15.0 × 10 -5 M)] ε = 3400 M -1 cm -1 (or 3.40 × 10 3 M -1 cm -1 ) 4. (3 points) Do the Plot: Beer's Law Plot y = 6686.8x + 0.0196 0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 0.0E+00 5.0E-05 1.0E-04 1.5E-04
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4C Pre-Lab Answer Key - ANSWER KEY: EXPERIMENT #4c - Iron...

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