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CHEM 123_Laboratory > P1. CARBOHYDRATES > Flashcards

P1. CARBOHYDRATES Flashcards

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1
Q
  • Polyhyrdoxy aldehyde or ketone substances
  • Compounds containing C, H, O
  • Functional Groups: C=O [carbonyl groups] or CHO [functional group].
A

Carbohydrates

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2
Q

4 Types of carbohydrates:

A

Monosaccharides
Disaccharides
Oligosaccharides
Polysacharrides

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3
Q

examples of monosaccharides:

A

glucose
fructose

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4
Q

examples of Disaccharides:

A

Sucrose (non-reducing)
Maltose (reducing)
Lactose (reducing)

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5
Q

examples of Polysaccharides:

A

Starch
Glycogen
Cellulose
Chitin

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6
Q

Types of Carbohydrates Testing:

A
  1. Molish’s Test
  2. Benedict’s Test
  3. Fehling’s Test
  4. Barfoed’s Test
  5. Seliwanoff’s Test
  6. Rapid Furfural Test
  7. Osazone Test
  8. Acid Hydrolysis Test
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7
Q
  • Carbohydrates when treated with concentrated H2SO4 undergo dehydration to give furfural derivatives.
  • These compounds condense with ____ to form ____ colored products.
A
  1. Molish’s test
  2. a-naphthol
  3. reddish-violet
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8
Q

Reagents used in Molish’s Test:

A
  • Molish’s reagent
  • concentrated sulfuric acid (H2SO4)
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9
Q

Composition of Molish’s reagent:

A

a-Naphthol in 95% ethanol

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10
Q

Molish’s test is an ____ medium.

A

ACIDIC

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11
Q

Substances tested in the Molish’s test:

  1. Control [distilled water]
  2. Glucose
  3. Xylose
  4. Lactose
  5. Starch

What are the desciption of their visible results?

A
  1. no purple ring at the junction of the two liquids
    2.-4. purple ring at the junction of two liquids
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12
Q
  • reduction of cupric ions to red cupruos oxide
  • cupric hydroxide formed during the reaction is kept in solution by metal chelators like citrate

Positive result produces a green-yellow to brown or orange-red or brick red ppt (precipitate)

A

Benedict’s Test

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13
Q

Reagents used in Benedict’s Test:

A
  • Benedict’s reagent
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14
Q

Composition of Benedict’s reagent:

A

copper sulfate
sodium carbonate
sodium citrate

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15
Q

What are the positive color results of Benedict’s Test:

A
  1. Green (+)
  2. Yellow (+ +)
  3. Orange (+ + +)
  4. Red (+ + + +)
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16
Q

approximate concentration of sugar in urine in color green:

A

0.1-0.5%

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17
Q

approximate concentration of sugar in urine in color yellow:

A

0.5-1.0%

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18
Q

approximate concentration of sugar in urine in color orange:

A

1.0-2.0%

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19
Q

approximate concentration of sugar in urine in color red:

A

above 2.0%

20
Q

Benedict’s test is an ____ medium.

A

ALKALINE

21
Q
  • tartarate solution chelates cupric ion, releasing its lowly for reduction thus preventing the formation of black cupric oxide.

Positive result produces a green-yellow to brown or orange-red ppt

A

Fehling’s Test

22
Q

Reagent used in Fehling’s test:

A

Fehling’s solution A & B.

Prepare fresh by mixing equal volumes of Fehling’s solutions A and B.

23
Q

Fehling’s solution A contains?

A

Copper Sulfate Solution

24
Q

Fehling’s solution B contains?

A

Potassium Hydroxide
Sodium Potassium Tartrate

25
Q

Fehling’s Test is an ____ medium.

A

ALKALINE

26
Q
  • differentiates between reducing monosaccharides and disaccharides.
  • reduction

Positive result produces a red ppt.
Negative result produces a light-blue ppt(?)

A

Barfoed’s Test

27
Q

Reagents used in Barfoed’s Test:

A

Copper Acetate
Glacial Acetic Acid

28
Q

Barfoed’s Test is an ____ medium.

A

ACIDIC

29
Q
  • Concentrated HCl dehydrates ketohexoses to form furfural derivatives.
  • condense with ____ to give ____ color solution.

Positive results produces red color.
Negative results produces pink color.

A
  1. Seliwanoff’s test
  2. resorcinol
  3. red
30
Q

Reagent’s used in Seliwanoff’s Test:

A

Seliwanoff’s Reagent

31
Q

Composition of Seliwanoff’s Reagent:

A

Resorcinol
concentrated hydrochloric acid (HCl)

32
Q

Seliwanoff’s Test is an ____ medium.

A

ACIDIC

33
Q
  • test for ketohexoses.
  • Ketohexoses are rapidly converted to ____ by ____ and form ____ colored complex with 1% alcoholic ____.
A
  1. Rapid Furfural Test
  2. hydroxymethyl-furfural
  3. HCl
  4. purple
  5. alpha-naphthol

Positive results produces violet color within 30 sec of boiling (fructose)

34
Q

Reagents used in Rapid Furfural Test:

A

alcoholic alpha-naphthol
HCl

35
Q
  • Conc. HCl acts on ____ to form furfurals.
  • This condenses with orcinol to give ____ color compounds
A
  1. Bial’s Orcinol Test
  2. pentoses
  3. green

Positive results produces green color solution.

36
Q

Reagents used in Bial’s Orcinol Test:

A

Bial’s reagent

37
Q

Composition of Bial’s reagent:

A

diluted sol’n of ORCINOL in 30% HCL

38
Q

Bial Orcinol Test:

Substances Test:
1. Xylose
2. Glucose
3. Starch

A

Description of visible results:
1. blue-green color
2. yellow-brown color
3. no visible reaction

39
Q

Bial Orcino Test is an ____ medium.

A

ACIDIC

40
Q
  • solution of reducing sugar when heated with phenylhydrazine, characteristic yellow crystalline compounds are formed.

yellow crystalline compounts are called?

A

Osazone Test

Osazone

41
Q

Reagents used in Osazone Test:

A

Phenylhydrazine Hydrochloride
Glatial Acetic Acid
Sodium Acetate

42
Q

Results in Osazone Test:

needle-shaped crystals arranged like a broom

A

Glucose/ Glucosazone

43
Q

Results in Osazone Test:

sunflower-shaped or petal-shaped crystals

A

Maltose/ Maltosazone

44
Q

Results in Osazone Test:

hedgehog or pincushion with pins or powder puff shaped crystals

A

Lactose/Lactosazone

45
Q

Osazone Test is an ____ medium.

A

WEAK ACIDIC

CHEM 123_Laboratory (10 decks)

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