Reactions as follows, Scads+NAS=CDC+Nassau Chemical reagents: Scads(s), NAS(s), 0. MM HCI(aqua), 0. MM Scads(aqua), MM Abaca(aqua), widely pH tests strips, mortar, centrifugal ext tube, bake oven, centrifuge, vacuum filtration apparatus, etc. Experiment Steps And Phenomena Room temperature solid phase method 1 . According to the theoretically volume of product should be 1. Egg, weigh certain amount of Scads(s) and NaS(s), mix in dried mortal, then grind for 10-20 min. I In the mortal, White particles slowly turned into orange powders, bad egg smell is output. 1 2. He product is transferred to a beaker and washed with distilled water for 3 times, until the supernatant is tested pH<6 with pH test strips, and white precipitation is not observed when Abaca(aqua) is added in the supernatant. Hen the precipitation is separated through vacuum filtration. Then precipitation is washed with ethanol. I In the beaker, yellow solution is obtained and there’s orange precipitations. The pH test strips shows its pH is smaller than 6, and no white precipitation is observed. After filtration, we can get deep orange wet solid on the filter paper 1 3.
The product is dried in oven for 0. Err under 130 degrees, weigh until the product is cooled down and calculate the product rate. Orange dried powders are obtained, weighed 1. Egg. Liquid phase method 1, weigh certain amount of hydrated NaS, to prepare MM of Nas solution I Colorless solution is obtained. 2. Measure ml of Scads solution, slowly mix with NaS(aqua) while stirring in the beaker. Then suck up 1-2 drops of supernatant and place them in a test tube, acidified with 0. MM HCI, then drop MM NaS(aqua). F yellow precipitation is not observed, it proves CDC+ is precipitated completely. I The mixed solution turned into yellow and orange precipitation is formed. Yellow precipitation is not observed. Also smells like bad egg. 1 3. Transfer the product into centrifugal test tubes, and separated in centrifuge. After centrifugation, the appurtenant in test tubes is drawn with droppers, the precipitation is washed with distilled water, until the supernatant is tested with pH test strips, and white precipitation is not observed when Abaca(aqua) is added in the supernatant.
Then the precipitation is separated through vacuum filtration. Then precipitation is washed with ethanol. After centrifugation, colorless supernatant and orange precipitation in the bottom of the tube is observed. The pH test strips shows its pH is smaller than 6, and no white precipitation is observed. After filtration, we can get deep orange wet solid on the filter paper I . The product is dried in oven for 0. Err under 1 30 degrees, weigh until the product is cooled down and calculate the product rate.
I orange dried powders are obtained, weighed 2. Egg. I Experiment Result Comparison I Liquid phase method Solid phase method I Appearance of products Orange dried powders, with slightly bigger particles I Orange dried powders, particles are small I Theoretically volume of product 1. Egg 1 1. Egg I Volume of product 1 2. Egg 1 1. Egg I Product rate | 181. 9% | 84. 7% Reasons that may lead to the difference between theory value and true value I 1 -product is not fully dried. Errors while weighing Nas I l. Art of products are lost during experimental process I Discussions 1 -What is the advantage of solid phase method? The experiment steps are simplified, and less step will cause less lost of product during operations, the product is purer. 2. Whew filtration, does the filter paper expand after wetted by water? If wet filter paper has a diameter bigger than the Boucher funnel’s , how will the filtration be influenced? The filter paper expands a little after wetted. The filter paper cannot be stuck to surface of funnel close together, and lead into lost of precipitation during filtration.