Question 2 of 5 Sapling Learning this Faculty and Staff at University of Califor

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Question 2 of 5 Sapling Learning this Faculty and Staff at University of California, Irvine was written by The following is a description of the preparation of an unknown sample 1. 0.0519g of an unknown Fe2 salt is measured and added to a 25 mL volumetric flask. 1.0 mL of 6 M HCI is added before diluting to volume 2. 1.0 mL of the solution prepared is transferred to a 100 mL volumetric flask. 1.25 mL of buffer and 5.0 mL of ferrozine is added before diluting to volume with DI water The absorbance of the solution in 2 is measured to be 0.895 Report all answers to 3 sig figs Absorbance vs. Concentration of Fe(lI) A. Calculate the concentration of solution 2. 1.4 -18.55x-0.0886 Number R2 = D·96504 1.2 mM B. Calculate the concentration of solution 1 (the original solution prepared) L.2 Number L.2 concentration F01mM mM C. Calculate the number of millimoles of the unknown solution (prepared by adding 0.0519g to 25 mL) Previous Give Up & View Solution O Check Answer Next Exit

Explanation / Answer

1) graph equation is

y = 18.55x - 0.0886

y = Absorbance ,0.895

x = Concentration

Therefore,

0.895 = 18.55x - 0.0886

18.55x = 0.9836

x = 0.0530M

Therefore,

Concentration Fe(II) in solution 2 = 0.053mM

2) Solution 1 is 100time diluted to get solution 2( 1ml to 100ml )

Therefore ,

Concentrtion Fe(II) in solution 1 = 0.053mM × 100 = 5.3mM

3) No of millimoles of in 25ml original solution = (5.3millimole/1000ml)×25ml = 0.1325millimole

4) Molar mass = Mass/No of mole

No of mole =No of millimole/1000= 0.0003125

mass of unknown = 0.0519g/0.0003125 = 166.08g/mol

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