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

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

Page
  1. 1
    1
  2. 2
    2
  • Essay length: 619 words
  • Submitted: 17/10/2006
  • Marked by teacher: (?) Adam Roberts
Share this essay:
Do not show me this again

Are you in the right place?

Jump to Biology and see how teachers think you should prepare in:

AS and A Level Exchange, Transport & Reproduction

Teacher essay summary

3 star(s)

A fairly good summary of the test method and reasons why some sugars are reducing and others not, but the chemical explanations are a little superficial and unclear in places.

Marked by teacher Adam Roberts 11/04/2013

The first 200 words of this essay...

Reducing and non-reducing sugars and the Test

Reducing Sugars (Benedict's test). All monosaccharide and most disaccharides (except sucrose) will reduce copper (II) sulphate, producing a precipitate of copper (I) oxide on heating, so they are called reducing sugars. Benedict's reagent is an aqueous solution of copper (II) sulphate, sodium carbonate and sodium citrate. To approximately 2 cm³ of test solution add an equal quantity of Benedict's reagent. Shake, and heat for a few minutes at 95°C in a water bath. A precipitate indicates reducing sugar. The colour and density of the precipitate gives an indication of the amount of reducing sugar present, so this test is semi-quantitative. The original pale blue colour means no reducing sugar, a green precipitate means relatively little sugar; a brown or red precipitate means progressively more sugar is present.

Non-reducing Sugars (Benedict's test). Sucrose is called a non-reducing sugar because it does not reduce copper sulphate, so there is no direct test for sucrose. However, if it is first hydrolysed (broken down) to its constituent monosaccharides (glucose and fructose), it will then give a positive Benedict's test. So sucrose is the only sugar that will give a negative Benedict's test

Read more
The above preview is unformatted text

Found what you're looking for?

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

  • "
    Markedbyteachers.com has really helped with my revision and is a valued resource for help with coursework. It has inspired me to write essays as good as the essays on the site. Definitely worth the investment.
    "
    Chris Mckellar. Media Studies, IT, English. A Level Student.
  • "
    This website has been a major help to me--I don't know what I would have done without it. You can depend on Markedbyteachers.com for solid, dependable essays.
    "
    Sabrina, Washington. IB English, History, Chemistry, Anthropology.

MbT essay summary

A fairly good summary of the test method and reasons why some sugars are reducing and others not, but the chemical explanations are a little superficial and unclear in places.

Marked by teacher Adam Roberts 11/04/2013

Marked by a teacher

This essay has been marked by one of our great teachers. You can read the full teachers notes when you download the essay.

Peer reviewed

This essay has been reviewed by one of our specialist student essay reviewing squad. Read the full review on the essay page.

Peer reviewed

This essay has been reviewed by one of our specialist student essay reviewing squad. Read the full review under the essay preview on this page.

Do not show me this again

Are you in the right place?

Jump to Biology and see how teachers think you should prepare in: