Chromatography: Separating Mixtures Introduction: Magic marker inks are often mixtures of several compounds. Paper chromatography is a common method of separating various components of a mixture. After separation, you can observe the different colors that make up a particular color of magic marker ink. You can also calculate a ratio Rf, which compares how far each compound traveled to how far each solvent (substance that dissolves another substance) traveled during the experiment. Rf = Ds/Df Ds = Distance traveled by the compound Df = Distance traveled by the solvent Materials: coffee filter, tape, isopropyl alcohol (rubbing alcohol), water, 3 different color magic markers (not permanent); 3 identical tall, narrow drinking glasses; metric ruler, 3 pencils Pre-lab Questions: 1.
Extraction and Drying: Using a separatory funnel, the cooled filtrate was extracted with 10ml of methylene chloride. After shaking our mixture, we broke and dried our emulsion by slowing passing the lower layer through a cotton ball layered with anhydrous magnesium sulfate. The extraction process was repeated 2 more times for maximum collection of the organic layer. Distillation: The extracts were poured into a 50ml round bottle flask and connected to a simple distillation apparatus. To obtain the caffeine, the methylene chloride was removed from the extract, leaving us with our solid caffeine residue.
In attempt to remove all the waste, I likely removed from 0.5mL of product. During the drying stage, 0.5g of anhydrous sodium sulfate was recommended to dry the crude ester, approximately 2g of anhydrous sodium sulfate was used. This seemed like an excess of anhydrous sodium sulfate but may not have affected the pure product in the long run. The product yielded produced a scent of a banana which is consistent with the production of banana oil. This equation displays the synthesis of isopentyl acetate by Fischer Esterification between isopentyl alcohol and acetic acid with sulfuric acid as the catalyst.
Lab 2 – Water Quality and Contamination Experiment 1: Effects of Groundwater Contamination Table 1: Water Observations (Smell, Color, Etc.) Beaker Observations 1 The water was colorless with a slight smell of chlorine. 2 The water has a slight yellow tint to it. It also appeared to be oily and then it surfaced to the top showing that there is two levels with water more dense than vegetable oil . 3 The vinegar has a stronger scent than the water and appeared to have a slight change in color but not too noticeable.
Method * Firstly create your solution of caffeine which you are going to use on the Daphnia, from 100% concentration (0.1) to 0% concentration (Pond water) * Secondly collect the Daphnia, using a pipette to extract one Daphnia from the fresh pond beaker. * Then try to get rid of excess pond water inside the pipette, so that only a couple of drops and the Daphnia remain. * Before placing your Daphnia on the slide, prepare a cotton wool to support the Daphnia to keep it stable, instead of mobile (this also gives a better view of the) * Now place the Daphnia and some water into a slide with a curved dimple in the middle, which can support the daphnia, also prevent light from the microscope to heat the Daphnia, affecting it. Make sure you hydrate to cotton wool so the Daphnia can survive. * Observe the Daphnia closer with the microscope, find the Daphnia heart.
Most coffee is grown in South America. The selected coffee beans are packaged in bags and then sent to roasting facilities. The flavour and smell of blends are achieved by blending the beans and careful roasting. The roasting is done in a large drum at about 260 deg Celsius for 20 minutes. The beans are cooled by pouring water onto it or by blowing cool air onto the beans.
Once dissolved, 24.9734 (± 0.0045)mL of acid was pipetted into an Erlenmeyer flask along with 25mL of cool (recently boiled) distilled water. Three drops of acid-base indicator, phenolphthalein, is added to the acid solution. Acid is titrated with the unknown base from the burette as the Erlenmeyer flask is consistently being swirled. Near the endpoint of 24mL, drops of base are added to the acid solution until a light pink colour persists within the solution. Titration is repeated 3 more times in order to achieve more accurate results.
When the compound had completely dissolved, 4-5 drops of ammonium hydroxide (NH4OH) was added to the solution in order to create a precipitate. As the NH4OH was added the solution became cloudy. Slowly 25mL of dimethylglyoxime (C4H8N2O2 or DMG) was added to the solution while stirring. As soon as the DMG was added it immediately turned pink and formed the Ni(DMG)2 precipitate. Below is the reaction equation for this.
Each organic extract is then dried over anhydrous calcium chloride pellets and evaporated to dryness. The extract is then wet with a minimal amount of dichloromethane and a sample of each is obtained and mixed together with 200 mg of alumina and again evaporated to dryness. This mixture is then placed in the prepared chromatography column and eluted with hexanes until the yellow β-carotene band is collected. The solvent is then switched to a 90/10 mix of hexanes and acetone to speed up the elution of the more polar lycopene band, which is also collected in its own flask. Each of these samples is evaporated to dryness and rehydrated with a minimal amount of dichloromethane.
The slide was flooded with malachite green before passing over to the flame several times until it “steamed”. The stain was replenished as it was continued to pass over the flame without letting it to boil. After it was rinsed with tap water, safranin was added as a counterstain. It was rinsed and air-dried before it was examined under OIO. B. Bacterial Capsules A small drop of nigrosin was placed near the edge of a clean slide.