AS3 PHOSPHORUS IN COPPER BY VISIBLE SPECTROPHOTOMETRY Last Revised: May 2015
1. REAGENTS & EQUIPMENT 1.1 HCl/HNO3 mixture (for copper dissolution) 1.2 1000 mg/L P standard solution 1.3 2.5 g/L ammonium vanadate 1.4 100 g/L ammonium molybdate 1.5 phosphorous‐free copper 1.6 copper sample 0.5‐1% P 2. PROCEDURE 2A. Prework You must complete the following questions before beginning the laboratory work. You will be provided with a procedure for the dissolution and colour formation steps after this. 2.1 You are required to use THREE calibration standards (not including the blank). What would be appropriate concentrations, given that the maximum is 20 mg/L? 2.2 How will you prepare them from the stock 1000 mg/L standard, assuming the final volume will be 100 mL? You will need an intermediate standard. 2.3 What approximate sample mass should you weigh out, given the expected concentration is 0.5‐1% w/w? 2.4 Other than P and the colorimetric reagents, what else should be added to the standards? 2B. Solution preparation and analysis 2.5 Insert your sample and standard values into the provided method. 2.6 Prepare sample and standard solutions. 2.7 Measure absorbances of all solutions. REPORT Calculations 
Plot a calibration graph for the standards. 
Determinate the concentration of P in the sample solutions. 
Calculate the mass of P in each sample solution. 
Calculate %w/w P in each sample. 
Calculate the average %w/w P in the alloy. Discussion 
explain the purpose of the molybdate and vanadate solutions Questions 1.
Explain why the more common colorimetric method for P known as the Molybdenum Blue method (because of the colour formed) would be unsuitable for this analysis. 2.
What is the functional of phosphorous in copper and copper alloys? There is a guide to this Exercise, including help with the calculations, on the website. AS3 p2 AS3. P IN COPPER
RESULTS SHEET
Sample 1 mass (g) Sample 2 mass (g) Sample 3 mass (g) Abs. Standard 1 Standard 2 Standard 3 Sample 1 Sample 2 Sample 3