1 / 10

Experiment 33: Colorimetric determination of iron

Experiment 33: Colorimetric determination of iron. PURPOSE To become aquainted with the principles of colorimetric analysis. THEORY. When mixed with phenanthroline , Fe 2+ ions reacts to form an orange red complex

lane
Download Presentation

Experiment 33: Colorimetric determination of iron

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Experiment 33: Colorimetric determinationof iron PURPOSE To become aquainted with the principles of colorimetric analysis.

  2. THEORY • When mixed with phenanthroline , Fe2+ions reacts to form an orange red complex • The color of the solution is directly proportional to the concentration of Fe3+ions present. The concentration of these ions can be determined by measuring the absorbance of a unknown Fe2+ complex solution and comparing it with the absorbance of a solution of known concentration. • Colorimeters measure the amount of light that is transmitted or absorbed by a solution. A description of how they work can be found in your text book • Fe3+(aq) needs to be reduced to Fe2+ by adding hydroxlyamine

  3. SAFETY PROCEDURES • Follow all instructions for using the equipment in this activity. • 2. Wear safety glasses and a laboratory coat for this experiment. • 3. Do not throw any waste down the sink.

  4. Part 1. Preparation of calibration curve • Pipet1.00, 2.00, 3.00, 4.00, and 5.00 ml of standard Fe solutioninto a 50 ml volumetric flasks 1 – 5 respectively • Add to each flask • 1ml of 1M ammonium acetate • 1ml of 10% hydroxylamine • 10 ml of .30% phenanthroline • Dilute the rest to 50 ml with water

  5. Part 1. Preparation of calibration curve • Mix well • Let sit for 40 minutes for the color to develop • Clean six cuvettes • Add water to one cuvette ½ way and calibrate spectrophotometer to 510 nm • Fill the other 5 cuvettes ½ way with a solution of increasing concentration • Record absorbance

  6. Part 1. calibration curve • graph concentration of Fe+2 complex (mg/ml) vs absorbance • Absorbance on y axis and concentration on x as seen on page 425

  7. calibration curve • Prepare calibration curve by plotting absorbance vs concentration

  8. Part B: Determination of Fe+3 complex • Weigh 0.1 g to 4 sig figs of Fe unknown into a 50 ml volumetric flasks • Add • 5 drop of 6 M sulfuric acid • Dilute the rest to 50 ml with water • Transfer to a 125 erlenmeyer flask Create Fe +2 ion

  9. Part B: Determination of Fe+3 complex • Pipet 1ml of Fe +2 ion from the erlenmeyer flaskinto three 50 ml volumetric flasks • Add to each flask • 1ml of 1M ammonium acetate • 1ml of 10% hydroxylamine • 10 ml of .30% phenanthroline • Dilute the rest to 50 ml with water Convert Fe +2 ion toFe+3 complex

  10. Part B: Determination of Fe+3 complex Mix well Let sit for 40 minutes for the color to develop • Clean 3 cuvettes • Fill the 3 cuvettes ½ way with each Fe+3 complex solution • Record absorbanceat 510 nm • Using the absorbance determine concentration of Fe+2 complex (mg/ml) by extrapolating from your graph

More Related