Use a stopwatch to track the time of the combustion of ethanol. While the water within the beaker is being heated, use a stirring rod to stir it. Put the fire out when 4 minutes have elapsed. For safety precautions, let it cool off a bit before using the scale to measure and record, the final mass of the alcohol burner containing the ethanol. Subtract the mass of the alcohol burner gained in step 4 to achieve the final mass of the alcohol.
Continue heating, while mixing intermittently, until agar is completely dissolved and the solution is clear. NOTE: Use heat-resistant gloves to handle flask after heating. Failing to do so may cause burn or serious injury. 2. Place melted agar solution and pre-warmed 2x culture medium in an ice bucket filled with hot tap water (42 °C).
Once the cola starts to boil, continue to boil it for another 10 minutes so that the carbon dioxide is removed. When the cola has finished boiling, cool it in an ice bath and pour the cola back in the volumetric flask and use distilled water to fill the flask to compensate for the evaporated water. Using a volumetric pipette, transfer 60ml of the cola to a beaker and put the magnetic stirrer in the beaker. Submerge the conductivity probe in the cola. Fill up the burette with NaOH
To prepare for the lab, fill one 600 mL beaker ⅔ full with tap water (roughly 400 mL full) and place on a hot plate with a thermometer. This beaker’s temperature needs to stay constant at 60℃ so the hot plate settings may need to be adjusted throughout the lab. Next, fill the 1000 mL beaker ⅔ full with cool tap water (roughly 700mL full) and place a thermometer in it. Set this beaker aside and maintain a temperature of roughly 25℃. Place the test tube of benzoic acid/lauric acid in the 60℃ water on the hot plate and when the solid solution begins to melt place the thermometer that was in the water into the test tube.
I. Introduction Caffeine as we all know is a kind of stimulant in our central nervous system and classified as methylxanthine. It also stimulates some other parts of our autonomic nervous system. This substance was mainly found in the seeds or leaves of a certain plant. A well known example of this plant is the coffee bean.
Once cool to touch the squeeze out all the tea bags carefully without tearing them apart. Using a separatory funnel extract three times with 15.0ml of dichloromethane gently rocking bath and forth the funnel venting the funnel often each time. Carefully decant into a pre-weighed 125ml flask and add the drying agent-calcium chloride pellets- and the organic layer was evaporated off in a warm water bath. Using aluminum foil as support around the mouth of the flask place test tube in the flask and heat the flask on a hot plate whilst adding water into the tube without letting it boil. Once the caffeine forms crystals around the test tube scrape off all the sublimed product and weigh the dried product 0.1grams of caffeine and had a melting point range of 175-230
In order to accomplish extraction of caffeine from tea, several methods should take place. First is a solid-liquid extraction must be done in order to get the solid product into the liquid solvent. Second is a liquid-liquid reaction to remove all impurities that are not needed. Third is to dry the compound to remove the traces of water. In order to get the percent yield of caffeine, compare the ratio between the weight of the isolated caffeine and the weight of the tea leaves and multiple it by 100.
Brookbond, Double-diamond, Godrej, Lipton, Lipton-Darjeeling and Marvel). Three separate stocks of tea liquor of different categories, volume 100mL have been prepared after adding 5 gm tea to 150mL water and boiling for 5 minutes. During experiment, the temperature of tea samples are maintained at 200C and pH values of all tea samples are maintained at 6.0 by adding buffer solution. The experiment were performed each time in a standard three electrodes configuration, containing four working electrodes (e.g. AG, PT, AU and GC ) having 5 mm length and diameter of 1 mm, counter electrode (made of stainless steel) having a dimension of 20x50 mm2, and Ag/AgCl, 3M KCL as reference electrode.
Hot water is much more efficient at dissolving caffeine then colder water. This is an example of solid/liquid extraction. Next, I added the water-tea mixture to a separatory funnel and added dichloromethane (DCM). DCM is an organic solvent and caffeine is much more soluble in it than compared to water. In turn, the caffeine dissolves into the DCM, which can be extracted later.