130 likes | 272 Views
Due Today: 1. Iron Content Analysis Pre-Lab 2. Neutralizing Power of Antacids Formal Lab Report Homework: 1. Iron Content Analysis Short Report 2. Prepare for Laboratory Final. Iron Content Analysis. Objective. Introduction to ultraviolet-visible (UV-Vis) spectroscopy
E N D
Due Today: 1. Iron Content Analysis Pre-Lab 2. Neutralizing Power of Antacids Formal Lab Report Homework: 1. Iron Content Analysis Short Report 2. Prepare for Laboratory Final Iron Content Analysis
Objective • Introduction to ultraviolet-visible (UV-Vis) spectroscopy • Introduction to analytical chemistry • Determine the iron content in vitamin tablets
Key Terms Visible Range: 700-400 nm UV Range: 10-400 nm
Key Terms • Spectroscopy – measuring the interaction of radiation with matter • Unique wavelength for each substance • Scanning – determine wavelength with maximum absorption • Chemists are most interested in the electromagnetic spectrum between 190-900 nm
Key Terms • Beer-Lambert Law - Absorbance of a solution is linearly related to concentration and identity of the chemical in solution • A: absorbance • b: extinction coefficient • c: concentration
Procedure Notes • Use Volumetric Glassware • Volumetric flask • Graduated pipets • Burets • Use stock solutions dispensed from burets
Procedure Notes • Wipe off the cuvette with a Kim-Wipe before inserting into the Spectrophotometer • Record the absorbances! • Record the advertised Iron content from both vitamin bottles!
Waste • Solutions can be disposed of down the drain
Risk assessment • Hydrochloric Acid • Danger • Inhalation Hazard • Corrosive
Risk assessment • Hydroquinone • Danger • Harmful if Swallowed • Skin Irritant
Risk assessment • o-phenanthroline • Danger • Toxic if swallowed
calculations • Molarity units: mg of Fe/100 mL • [Stock solution]= 40 mg/L=4 mg/100mL • V1= volume of stock iron solution in each trial • V2=100 mL (total volume)
calculations • Graphing in Excel • Force the trendline through (0,0) • Include the equation of the tendline and R2 value Y = mx A = bc