- Join over 1.2 million students every month
- Accelerate your learning by 29%
- Unlimited access from just £6.99 per month
Qualitative tests for carbohydrates
The first 200 words of this essay...
Qualitative Tests For Carbohydrates
In this practical experiment there are given , five known carbohydrate solutions. Namely Glucose, Fructose, Xylose, Starch and Sucrose (common table sugar). The first four are what are known as "reducing sugars" which in solution form either an aldehyde or a ketone. The latter, sucrose, is known as a "non-reducing" sugar. In addition to these is an unknown carbohydrate solution. There are qualitative food tests that are regularly used to identify the presence of these carbohydrates in foodstuffs. The following are a brief description of these well proven tests for each named carbohydrate.
a) The Molisch test for Carbohydrates - the result of this test shows positive where all carbohydrates are present. Monosaccharides (simple one sugar units) give a rapid positive test, whereas Disaccharides (double sugar units) react more slowly. This is due to the Molisch reagent (a-naphthol 95% in ethanol) either dehydrating pentoses (sugars with 5 carbon atoms) to form furfural and dehydrates hexoses (sugars with 6 carbon atoms) to form 5-hydroxymethyl furfural. The reaction of the Molisch reagent with these furfurals produces the purple product. A positive result produces a purple furfural product. (see fig.1) (www.harpercollege - Nov.
Found what you're looking for?
- Start learning 29% faster today
- Over 150,000 essays available
- Just £6.99 a month
Not the one? We have 100's more
Molecules & Cells (view all)
- Cellular Structure and Function
- Measurement of protein solutions concentrations by biuret pr...
- The digestive system
- An investigation of the enzyme catalysed hydrolysis of urea ...
- Cellular Respiration and the Role of Mitochondria
- Colorimetry Experiment - I will investigate and observe the ...
- Experiment Aim: To investigate the effects of placing onion ...
- Influenza is a viral infection which attacks the respiratory...
- How the protein insulin is made.
- This essay will look at different types of human tissues and...
""George Boustred English, Maths, Science, Resistant Materials, History, Music. GCSE Student
""Zoia, London. GCSE Student. 'English, Science, RE, Geography, History.'