28 Quantitative Determination of Metals Part A. Spectrophotometric Determination of the Content of Iron (II) in a Vitamins Pill
Fotis Nifiatis
Learning Objectives
A commercial vitamin pill will be analyzed for its iron (II) content. The students will learn to perform a series of dilutions, use a spectrophotometer, and construct a calibration curve. Course Objective: “Determine solution concentrations and calculate the amounts of materials involved in solution reactions.” HIP Activity: Collaborative Projects Digital Tool: Students will use a spectrophotometer to collect data and Excel to analyze their data.
Purpose/Rationale
Instructions
Students in groups of three (3) will prepare an Iron (II) stock solution of Iron. Further dilutions will result in 5 diluted solutions. A portion of each solution will be converted to a species (by reacting it with a chelate agent) with a large absorbance in the UV-Vis region of the electromagnetic radiation. A photo spectrometer will be used to measure the absorption of each solution. Similarly, the Iron (II) will be isolated from a commercially available vitamin pill, and reaction with the same chelate agent as above will result in a strongly absorbent complex. Its absorption will also be determined under identical conditions. Data analysis (calculation of new concentrations and creation of a calibration curve) will result in the concentration and actual of Iron (II) in the commercially available vitamin pill. Detailed instructions will be delivered as a PowerPoint presentation will be used for the introduction of the experiment. The presentation will be shared with the students.
Format Requirements
Each group should write a formal report including the following paragraphs.
- Purpose of the experiment (a couple of lines)
- Reaction (use chemical symbols only)
- Physical properties and hazards (for all chemicals used)
- Procedure (describe what you did)
- Data (tables only)
- Data analysis (include all calculations and graphs)
- Conclusion (Calculate % error for Iron (II) measured versus the stated by the manufacturer amount.) Include references.
Rubric/Criteria
This report will be graded out of 100, like any other report.
- Purpose of the experiment (5 pts)
- Reaction (5 pts)
- Physical properties and hazards (20 pts)
- Procedure (10 pts)
- Raw data (10 pts)
- Data analysis (35 pts)
- Conclusion (15 pts)
