Submission of Proposal under Star College Scheme

Result:

1. 
   The solubility of KCl in water is _______ g/cm³ 2. The nature of graph_______
   

Project: 11
Spectrophotometric Determination of Iron in Vitamin Tablets


Principle:
In this experiment, iron from a vitamin supplement tablet is dissolved in hydrochloric acid and thenreduced to Fe⁺²with hydroquinone:
While freshly-dissolved Fe⁺²in aqueous solution is nearly colorless, we can impart an intense redcolor by a stoichiometric reaction of Fe⁺²with three molecules of o-phenanthroline:
The complex, which is often written as Fe(phen)₃⁺², has a maximum in its absorption spectrum
close to 510 nm (the literature value for λmax is 508 nm.) Measuring the solution’s absorbance at
λmax is therefore an accurate method of determining Fe concentration.

Both standard solutions of Fe(phen)₃⁺²and a solution with Fe from vitamin tablet has to be prepared, and measure their absorbance on Spectrophotometer/Colorimeter. Construction of a calibration curve will allow you to determine both the molar absorptivity of the Fe(phen)₃⁺²

complex, and the milligrams of Fe in vitamin tablet.
Experimental Procedure

1. 
   Reagents required:
   

• 
  Hydroquinone: Solution containing 10 g/L in water.(90mM)
  
• 
  Sodium citrate: 25 g/L in water.(96mM)
  
• 
  o-Phenanthroline: 2.5 g in 100 mL of ethanol and 900 mL of water. (The ethanol helps dissolve the rather non-polar o-phenanthroline.),13.87mM
  
• 
  Stock Fe⁺²(nominally 0.04 mg Fe/mL): Prepare by dissolving 0.28 g of reagentgrade
  
• 
  Fe(NH4)2(SO4)2·6H2O in water in a 1L volumetric flask containing 1 mL of98 wt % H₂SO₄.0.714mM .