Test of Procedure to Analyze for Copper in Ore Samples

Several solutions were made by dissolving small pieces of chrysocolla ore in 20 mL of 1.0 M H2SO4, then filtering and diluting to 250 mL with water. Then 25 mL diluted solution was mixed with 10 mL of 6 M NH3(aq) and diluted to 50 mL. Absorbance measurements gave the following results: