Spectrophotometric Measurement of CoCl2(continued) QUESTION The absorbance of 0.49 recorded with the unknown sample in t

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Spectrophotometric Measurement Of Cocl2 Continued Question The Absorbance Of 0 49 Recorded With The Unknown Sample In T 1 (47.19 KiB) Viewed 127 times

Spectrophotometric Measurement Of Cocl2 Continued Question The Absorbance Of 0 49 Recorded With The Unknown Sample In T 2 (28.4 KiB) Viewed 127 times

Spectrophotometric Measurement of CoCl2(continued) QUESTION The absorbance of 0.49 recorded with the unknown sample in the previous Question #5 is not within the dynamic range of the spectrometer (0.15-0.42) that was obtained with the standards in Question #4 Thus, the CoCl, concentration you determined in Question #5 may not be as accurate as it should be. To ensure a more accurate determination of the concentration, you will need to make the absorbance value fall within the dynamic range of the instrument you obtained in Question #4. But how? You will achieve this mission by diluting the original unknown sample in Question #5. Since you are not sure about how much you should dilute, you will prepare at least two diluted samples: 25% dilution and 50% dilution of the original unknown sample You will then measure the absorbance of each diluted sample and calculate the corresponding concentration. But before you work on that here, you will first work on the dilutioris themselves by completing the table below. Diluting the Original Sample Whose Coci, Concentration is unknown (the Sample in Question #5) Dilution of the Original Unknown Volume of the Original Unknown, ml. Volume of Distilled Water, ml 25% dilution 10 A? 50% dilution 10 B? Ovo artigos Recenas by The Alis ml The 37 mL
Calibrating Spectrophotometer Analytical instruments in general have two limiting aspects in their performance. First, almost all analytical instruments do not automatically give out the results in the way you want. Second, no analytical instruments give out the results that reflect in perfect proportion to the amounts that are the samples. For example, though your goal in this lab is to determine, in molarity, how much Coci, are dissolved in the samples, the spectrometer you will use never gives out the results like 1.0 M 2.0 M, 3.0 M and so forth. Instead, it will give out in the amount of absorbance of light which is proportional to the amount of CoCl. This is the first limiting aspect. The second limiting aspect is that the spectrometer does not give out the amounts of absorbance like 100, 200, 300 and so forth, respectively, that are in perfect proportion to the Coch amounts of 1.0M 2.0 M, 3.0 M and so forth. Instead, it rather gives out the absorbance amounts like 100, 207, 305, respectively, To overcome these limitations, you wil tame the spectrophotometer, the process caled calbration. Using the set of samples whose concentrations you already know (we cal such set the standards), you will find out the corresponding set of absorbances after running the standards through the instrument. You will then correlate the standards with their corresponding absorbances. This correlation you will do is the calibration of the spectrophotometer