Fermentation of Carbohydrates: Ethanol from Sucrose Essay

Objective To demonstrate a fermentation process, isolate the ethanol produced by uncomplete distillment, determine the composition of the ethanol solution recovered, and make stoichiometric and yield calculations.ProceduresFermentationWeigh forbidden 20.0 g of sucrose and place it into a 250-mL Erlenmeyer flask. Add hundred mL of water and gently jar until on the whole the sucrose has dissolved. To this solution add 0.60 g of dipotassium hydrogen inorganic phosphate (K), 1.8 g of sodium phosphate hydrate (Na3PO412HO) and 2.0 g of dried bakers yeast. Vigorously shake the contents to mix them thoroughly. The Erlenmeyer flask is fitted with a one-hole rubber stopper containing a short piece of glass tubing. Latex tubing (8 -12 in.) is attach to the glass tubing. An overhand knot is loosely tied in the tubing. The low part of the loop is change with just enough water so that the passage is blocked, but gas from the fermenting chamber go forth be able to push the water out of the way and escape (brewers call this an behaviorlock). This frame-up excludes air (and oxygen) from the system (which allows anaerobic oxidation) and prevents further oxidation (by aerobic oxidation) of the ethanol to acetic acid. Label the fermentation frame-up with your name and place the flask in the incubator chamberIsolation by Fractional distillateDo not shake the flask avoid disturbing the sediment on the bottom commove your flask from the incubator bath or chamber. Carefully remove the rubber stopper from the 250-mL Erlenmeyer flask. Prepare a vacuum filtration assembly using both 250-mL side-arm filter flasks, a 5.5-cm Buchner funnel (with a drivelvac or neoprene adapter), and two lengths (each 12 in.) of vacuum tubing. N.B. We use the second flask so between the aspirator and our filter flask so that the filtrate exit not become contaminated if tap water is pulled back through the hose. train a piece of filter paper into the Buchner funnel so that it covers all the holes and lies flat. Into a250-mL beaker, place 100 mL of water and one tablespoon of Celite. Stir vigorously and pour the mixture into the Buchner funnel eon the water is running and a vacuum is applied. A thin layer of the Celite Filter Aid ordain form on the filter paper. Discard the water pull ined in the filter flask.Do not suck besides much air through the filter pad if it dries, it may crack and be unusable. Carefully decant the liquid in the fermentation flask above the sediment through the Celite Filter Aid, using suction. This technique traps the small yeast particles in the Celite Filter Aid but lets through water, ethanol, and each other liquid impurities. This liquid filtrate will be distilled. Obtain a distillation setup and assemble the glassware for distillation. Note the placement of the thermometer bulb in the adapter take-off to the condenser. Securely clamp the implement and condenser, and secure joints with plastic clips. Use a small dab of silicone grease on all the standard-taper joints as you connect them. Collect the distillate in a graduated cylinder.Use a round-bottomed distilling flask that will be filled approximately one-half to twothirds full a 250-mL round-bottom flask should do. Add 2-3 boiling stones to the flask. Use a heating mantle for the heat source and a Variac to check out the heat. Your mantle may have a built in voltage controller. Gradually turn up the heat until the liquid in the distillation flask begins to boil. As the vapors rise in the head, you will see liquid condensing this ring of condensate will rise in the column. Control the range on the Variac so that the condensate rises slowly through the column and at an even rate. (If the rate is too fast, the column will flood.) The temperature readings at the distillation head will rise when the temperature reaches (about) 78C, begin to collect the liquid that distills.Discard any liquid distilling before this temperature is reached. Collect liquid distill ing between 78 and 90C. Collect 10-15 mL of distillate. Turn off the heat source and remove the heating mantle from the distillation flask. Weigh a 50-mL beaker to the nearest 0.001 g. With a 10-mL volumetric pipet, transfer 10 mL of distillate to the beaker (V). Do not pipet with your mouth use a pipet bulb. Reweigh the beaker and liquid (5), and by difference, determine the weighting of the distillate. Determine the density,and by referring to the graph, determine the percent composition of the ethanol.