• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7
  8. 8
  9. 9
  10. 10
  11. 11
  12. 12
  13. 13
  14. 14
  15. 15
  16. 16
  17. 17
  18. 18

Obtain pure samples of Ethanol (CH3CH2OH) and Ethanoic Acid (CH3COOH) from fermented Yeast (Saccharomyces Cerevisiae).

Extracts from this document...


PREPARATION OF ETHANOL AND ETHANOIC ACID AIM: To obtain pure samples of Ethanol (CH3CH2OH) and Ethanoic Acid (CH3COOH) from fermented Yeast (Saccharomyces Cerevisiae). BACKGROUND INFORMATION: The use of yeast in food production is the oldest and most extensive contribution made by any group of microorganisms. A most common substrate that yeast can work with is GLUCOSE. Glucose is a monosaccharide, which are sweet crystalline sugars that dissolve easily in water to form sweet solutions. Monosaccharides have the general formula (CH2O)n and consist of a single sugar molecule. Glucose is the simplest and most common monosaccharide. It is a Hexose sugar and therefore has the formula C6H12O6. Glucose can exist in two possible ring forms, known as the alpha (?) and beta (?) forms: The hydroxyl group on Carbon atom 1 can project below the ring (? glucose) or above the ring (? glucose). Molecules like this, which have the same molecular formula but a different structural formula, are said to be ISOMERS of each other. One type of isomerism, called sterioisomerism, occurs when the same atoms or groups, are joined together but differ in their arrangement in space. The existence of two isomers of glucose is important because it is linked to the way in which polysaccharides are formed and subsequently their roles. A glucose molecule can switch spontaneously from the open chain form to either of the two ring forms and back again. As glucose is respiratory substrate, it is a very important source of energy in living organisms. Glucose is an important building block as it is used to build up more complex carbohydrates e.g. Starch, Glycogen and Cellulose. It is a substrate, which gets broken down by the enzymes in the yeast. ENZYMES are defined as biological catalysts. A catalyst is a substance, which speeds up a chemical reaction, but remains unchanged itself throughout the whole reaction. Enzymes are biological because they are protein molecules made by living cells. ...read more.


and out into the sink. This water does not come in contact with the actual ethanol solution being heated; its purpose is only to keep the apparatus cool. At the bottom of the condenser there is an opening to which a receiver adapter is connected which delivers the distilled ethanol into a conical flask. The apparatus was held in place using two clamp stands. Inside the ethanol solution some anti bumping granules were added in to keep the movement if liquid under control. Once all the apparatus was set up, the Bunsen burner was lit on the orange flame (hole fully opened). The Bunsen burner was resting on a heatproof mat, which protects the surface underneath. Extra car and precautions were taken whilst lighting the Bunsen. A lab coat was worn to protect clothing, all long hair was tied back to prevent it catching alight if it came in contact with the flames and most important of all, safety spectacles were worn to protect the eyes from getting damaged if anything was to go wrong. The Bunsen flame changed to the blue flame but not roaring, as this would be too high. The ethanol solution was heated until the temperature reached 70oc. Care was taken that the temperature would not rise above this by keep taking the Bunsen away from underneath the experiment. This had to be repeated several times before enough ethanol was collected for the next stage. At one time the temperature had risen above 70oc which ruined the experiment. The reason being that ethanol condenses at roughly 70oc and when the temperature went above this, other products also condensed therefor the ethanol obtained was not pure. To correct this mistake the liquid collected in the conical flask was poured back into the pear-shaped flask by lifting the tube above the flask Once the temperature reached 70oc the Bunsen was moved away quickly. ...read more.


In beer production to get different types of them, different yeasts are used compared to vinegar production. These yeast can also tolerate higher temperatures compared to the yeasts used for vinegar production. The reaction conditions used in beer and vinegar productions are different. In beer manufacturing a number of stages have to be carried out. These are malting, milling, mashing, sparging, boiling, cooling fermentation and conditioning of the end result, beer. The temperatures used are very high and on the whole the manufacturing of beer is a lengthy process. Recently, there have been developments to produce both wine and beer by continous fermentation methods. In these processes, the yeast is kept in its exponential growth phase, so the product is made much more quickly. This process is particularly popular for making lager, which can be made in about four hours instead of several days. However, although this process is more economical, the flavour and alcohol content are reduced. Vinegar is produced by the oxidation of ethanol. Traces of other compounds such as esters, alcohols and organic acids give variations in the flavour. The source of material used for the initial alcoholic fermentation reflects materially locally available i.e. cider vinegar comes from the fermentation of apple jiuce, wine vinegar comes from grape juice, malt vinegar from barley or other cereal that has undergone the malting process and rice vinegar from rice. Traditional methods developed for the commercial production of vinegar encourage the aerobic activity of bacteria such as ACETOBACTER and GLUCONOBACTER. The slow methods produce a high quality vinegar, whereas that produced by the quicker methods tends to have poorer flavour. The quality can be improved by allowing the vinegar to undergo a maturation process, standing in barrels. The vinegar is generously pasteurised by heating for a few seconds at 60 - 66 degrees. What we carried out was much simple compared to industrial processes i.e. in industry, different yeasts and enzymes are used to get the required product. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Aqueous Chemistry section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Aqueous Chemistry essays

  1. Determine the concentration or molarity of Ethanoic acid (CH3COOH) in two types of commercial ...

    The alkali being added can then stop being added. This was done in the preliminary experiment: a range of indicators were taken (full range indicator, screened methyl orange and phenolphthalein). These were put into test tubes and 1 cm3 of 0.1 M sodium hydroxide (the alkali being used for this titration)

  2. Recrystallization - choose the most appropriate solvent to obtain a successful recrystallization of benzoic ...

    all of the crystals moving freely by swirling the flask and occasionally it will be necessary to add more ice-cold solvent in order to transfer the last of the crystalline material. It may also be necessary to dislodge crystalline material from the sides of the flask with a spatula prior to flirtation.

  1. Back Titration to find the Concentration of Vinegar (Ethanoic Acid)

    This is used as an indicator for the colour change as and when the neutralisation stage occurs. The sulphuric acid was then carefully drawn up into the second 2cm3 micropipette and attached to the clamp on the well plate. In the first well of sodium hydroxide, the sulphuric acid was titrated drop by drop.

  2. How much Iron (II) in 100 grams of Spinach Oleracea?

    Moles = 0.0000525 mol dm-3 The ratio of Potassium Manganate (VII) (aq) to Iron (II) (aq) is 3:5 and therefore to work out the mols of Iron (II) used in the titration I need to divide the volume of moles by 3 and then multiply it by 5.

  1. Determine the enthalpy of neutralization for HCl +NaOH, CH3COOH +NaOH, and 1/2H2SO4 +NaOH.

    The beaker was placed in an insulated calorimeter and the initial temperature recorded using a mercury thermometer. 3. 25 cm3 of a aqueous NaOH (1.04M) was added to the dilute HCl and the apparatus stirred after the lid was closed 4.

  2. The oxidation of Ethanol.

    Below are the hazards. Ethanol - Highly flammable above 13�C causing a narcotic effect if inhalation of the vapour occurs. Toxic Dangerous with � Oxidising Agents - incontrollable reactions take place � Bromine � Mercury (??) � Silver Nitrate � Platinum � Potassium Ethanal - Extremely flammable above -27�C Harmful

  1. Analysing the ethanoic acid concentration in different types of vinegars.

    Firstly I will need to make a standard solution of NaOH to titrate my vinegars with. I will make it by mixing sodium hydroxide pellets with distilled water. To do this I will need: 250cm3 volumetric flask NaOH pellets Distilled water Weighing scales Plastic boat Pipette (fine toothed)


    The experimental errors in this experiment can be when heating up the soil; the soil might have been burned. Another error is that when the cooled basin is weighed it might be contaminated. Weighing the soil on the balance with some samples left on the balance can give wrong results.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work