• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Determine which of the three sugars tested (Glucose, Fructose and Sucrose) is a reducing sugar by heating them with Benedict's solution.

Extracts from this document...

Introduction

QUALITATIVE EXPERIMENT [REDUCING SUGARS] AIM: To determine which of the three sugars tested (Glucose, Fructose and Sucrose) is a reducing sugar by heating them with Benedict's solution. BACKGROUND INFORMATION: A carbohydrate is an organic compound that is composed of atoms of Carbon, Hydrogen and Oxygen in the ratio 1:2:1. Carbohydrates used in the experiment can be divided into two groups: > Monosaccharides: All monosaccharides have the general formula (CH2O) n; where 'n' can be any number between 3 and 9. All monosaccharides also contain a carbonyl (C=O) group and at least two hydroxyl (OH) groups. The monosaccharides used in this experiment are called Hexose, which have six carbon sugars. All the hexoses have the general formula C6H12O6. They can exist as straight chains or rings. Two common hexoses are glucose and fructose (see figure below). Hexoses are sources of energy in respiration and are the monomers, which link together to form disaccharides and polysaccharides. ...read more.

Middle

1. Set up the apparatus as shown above in the diagram. 2. Fill the beaker with water. 3. Add 2cm3 of a sugar to the boiling tube i.e. Glucose, Fructose or Sucrose (Label the boiling tubes with the sugar it contains). 4. Add 2cm3 of Benedict's solution to each of the test tubes. 5. Place the three boiling tubes in the water bath and heat it. 6. Continue heating until the glucose and fructose solutions change colour. > Results: Name of Sugar Original Colour Colour Change Final Colour Glucose Blue Green Brick-red Fructose Blue Turquoise Orange-red Precipitate Sucrose Blue No change Blue CONCLUSION: The above results prove that my prediction was correct. Glucose and fructose change colour to prove that they are reducing sugars and sucrose does not change colour proving that it is a non-reducing sugar. Glucose is able to reduce the copper (II) [Cu++] in the copper sulphate to copper (I) ...read more.

Conclusion

4. Add 1 cm3 of dilute hydrochloric acid to the test tube. 5. Place the boiling tube in the water bath and heat it. 6. Heat the solution for 3 minutes. 7. Let the solution cool. 8. Add 1 cm3 of Benedict's reagent to the above solution. 9. Place the test tube in the water bath. 10. Heat the solution until it changes colour. Result/Analysis: A brown-red precipitate occurs. This happens because sucrose has been hydrolysed (this reaction involves the breaking of a bond, between the two subunits of a large molecule, by the addition of H (hydrogen) and OH (hydroxide) from a water molecule) into its constituent monosaccharides: glucose and fructose. (Although sucrose has reduced copper (II) to copper (I) that does not make it a reducing sugar because it was actually the glucose and fructose that make up sucrose that reduced copper (II) to copper (I).) All the results obtained in the experiment are positive thus the experiment has been successful and the aim has been achieved. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Exchange, Transport & Reproduction 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 AS and A Level Exchange, Transport & Reproduction essays

  1. Marked by a teacher

    Investigating and testing for reducing and non-reducing sugars

    3 star(s)

    In between each I used universal indicator paper to test whether the solutions were neutral (green). I continued until each solution was neutral. * Finally, I re-boiled the kettle and re-filled the beaker with the water (the hotter the better).

  2. Marked by a teacher

    Aim: To test for reducing sugars using glucose, sucrose and lactose to see which ...

    3 star(s)

    Method 1. First mix the one of the sample with about 5cm of distilled water in a test tube. 2. Then add 3cm of Benedict's reagent using a syringe in to a test tube. 3. Repeat for the other two samples then place the sample in to a test tube holder.

  1. Peer reviewed

    The comparison of antibacterial properties of herbal products and standard antibiotics

    5 star(s)

    Label each plate with the bacteria name, the herbal oil or the antibiotic name, the date and your initials. 17. Repeat the above steps but use M.luteus bacteria instead. 18. Clean up all your mess. 19. Once finished, place all the agar plates in the incubator at 25?. 20.

  2. Peer reviewed

    "An investigation into the Respiration of Carbohydrate Substrates by Yeast."

    5 star(s)

    I predict this because the commercial purposes of Baker's and Brewer's yeasts are different and therefore special cultivations might have made the yeast better designed for one purpose than the other. Again a null hypothesis was also adopted; Null hypothesis two: 'There will be no significant difference between the amount

  1. Rate of Respiration

    40 �C 7 40 �C Lactose 0 0 0 0 0 0.1 0.1 0.1 0.1 0.2 7 40 �C 7 40 �C 0 0 0 0 0.2 0.2 0.2 0.2 0.2 0.3 7 40 �C 7 40 �C Average 0 0 0 0 0.1 0.2 0.2 0.2 0.2 0.3 7

  2. A Colorimetric method for the estimation of glucose (or reducing sugars) in solution.

    solution * 20cm3 0.01m potassium mangante * 50cm3 1m sulphuric acid * Two 10cm3 plastic syringes * Eight test tubes * Test tube rack * Beakers Fair testing In order for the experiment to be fair there have to be three types of variables that need to be taken into consideration.

  1. Free essay

    Why does the colour leak out of a cooked beetroot?

    Some of the proteins span the membrane. Other proteins are found only within the inner layer and some only within the outer layer. Membrane proteins have hydrophobic areas and these are positioned within the membrane bilayer [2]. The Figure 1[c] below shows the cell membrane. Some of the proteins are fixed within the membrane, but others can move around in the fluid phospholipid layer.

  2. Why did the colour leak out of cooked beetroot?

    Man has selected for colour in beetroot, both because it is more attractive but also because it may well be linked to genes for flavour too. There is no indication that they have any protective function (e.g. against UV light or insect/fungal/viral attack).

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