I need help answering these questions and understanding how to do them please (A

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I need help answering these questions and understanding how to do them please (Analytical Chemistry)
Analytical Chemistry Laboratory CHE 322-L51 Spring 2017 (Morse) lll. Pre-lab Assignment: Type this up as a document and submit it at the beginning of class independently of the laboratory notebook: Reading through the purpose and procedure of the lab and the recommended reading from the textbook may yield a more thorough understanding of the pre-lab assignment. Complete the following tasks but rewrite the instructions of each task before responding 1. What is the purpose of the addition of the hydroquinone? (1 point) 2. What is the purpose of the addition of the o-phenanthroline?( point) 3. Which species is the target for absorption of light at 510 nm? (1 point) 4. What is the ratio of moles of Fe' in the tablet to moles of the absorbing species 5. Calculate the concentration of Fe" ons in ug/ml) in a solution that has been prepared by diluting a 50.0 mL aliquot of a 19.3 ug/mL Fe to 1000.0 mL. Clearly show any required calculations with proper units and significant digits. G points) 6. Calculate the mass, in milligrams, of iron in a tablet if the concentration of iron (Fe was determined to be 21.7 ug/mL in a 100.0 mL solution that was prepared from a 25.0 mL aliquot of a 250.0 mL solution into which one complete tablet was dissolved. Clearly show any required calculations with proper units and significant digits. [Hint: draw diagrams of the solutions and aliquots to determine the fraction of the iron tablet that was present in the 100.0 ml. solution.] (3 points)

Explanation / Answer

1. Hydroquinone is the reducing agent which reduces all the Fe^3+ to Fe^2+ which then reacts with phenanthrolene

2. phenanthrolene forms a complex with Fe^2+ which has a strong absorption at 510nm

3. Species is Fe(phen)3^2+

4.Ratio is 1: 3 . 1 part Fe^2+ and 3 part pheanthrolene

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