QUESTION 4 Which of the following statements are true about spectrophotormetry a

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QUESTION 4 Which of the following statements are true about spectrophotormetry and Beer's Law? Select allthat apply 5 points The value used for the molar absorptivity varies depending on what compound the analyte is and what wavelength is being used. The sample with the higher concentration will have the higher percent transmittence. A wavelength selector, such as a monochromater, is placed between the light source and the sample so only one wavelength of light interacts with the sample. A sample that has a high percent transmittance will have a low absorbance. If the absorbance of a sample is too low to accurately read, you should try using a cuvette with a shorter path length. J Beer's law is only valid when the analyte is at high concentrations. When plotting measurements of a solution that perfectly adheres to Bee's law with the absorbance of the solution is plotted on the y-axis and the conentration on the length. x-axis, the slope of the best fit line represents the product of the molar absorptivity and the path Spectrophotometers are most accurate between absorbance values of 0.1 and 2 The molar absorptivity value has units of cm*M 5 pointsS QUESTION 5 You are investigating the presence of iodine in the otherwise clean waste of a chemical treatment facility (ie. assume no matrix effects) First, you oxidize the I to l2 and then you form a bright green complex with the h using toluene. The molar absorptivity of the complex is 7.87+10 M cm at 635 nm. When performing this process using a 1.00 cm cuvette with a sample from the facility,you obtained an Click Save and Submit to saue and submit. Click Save All Answers to save all answers

Explanation / Answer

1 true

2. False, More concernated sample will have less transmittance.

3. True

4. True

5. False. It will further decrease absorption.

6. False, Beer’s Law successfully describes the behaviour of dilute solutions only. At high concentrations (ie greater than 10-2 M) there is interaction between absorbing particles such that the absorption characteristics of the analyte are affected.

7. True

8. False, Best results (minimum overall error) are obtained when absorbance is in the range 0.2 to 0.8.

9. False, unit is M -1 cm -1

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