Experiment No 1-4: Qualitative Analysis of Carbohydrates

Practice flashcards covering qualitative analysis tests for carbohydrates including Molish, Iodine, Benedict, Barfoed, Osazone, and Seliwanoff's tests as described in the lecture notes.

Molish test

A test used for the detection of carbohydrates in a compound, resulting in a purplish violet colored ring formed at the junction of the two solutions upon adding Molish reagent and $H_2SO_4$.

Molish reagent

A solution of $\alpha$-naphthalene (or $\alpha$-nephtol) used in the Molish test to identify the presence of carbohydrates.

Iodine Test

A test used for the identification of polysaccharides, specifically starch, which produces a blue color change.

Starch (Iodine Test)

A polysaccharide that gives a blue color when it reacts with 2-3 drops of Iodine solution.

Glucose (Iodine Test)

A monosaccharide that shows no change in the color of the iodine solution, indicating it is not a polysaccharide.

Benedict test

A test used to identify reducing sugars; a positive result is indicated by a green, yellow, orange, or red color change after boiling for 2 minutes.

Sucrose

A non-reducing sugar made up of glucose and fructose that does not have a hydroxyl group freely available for reaction, resulting in a negative Benedict test.

Hydrolysis test

A procedure where 3 drops of conc. $HCl$ are added to a sample and boiled for 2 minutes to break down sucrose into glucose and fructose, making it reactive to Benedict reagent.

Barfoed teste

A test used to identify monosaccharides where a red color precipitate forms within 3-5 minutes of heating in a boiling water bath.

Osazone test

A test used to confirm the presence of fructose by adding phenyl-hydrazine hydro-chloride, sodium acetate, and acetic acid, resulting in the formation of yellow color crystals.

Seliwonoffs teste

A test used to detect keto-sugar; it involves boiling the reagent and sample vigorously for 1 minute to produce a cherry red color.

Green colour (Benedict's)

An observation in the Benedict test indicating a low concentration of reducing sugar.

Yellow colour (Benedict's)

An observation in the Benedict test indicating a moderate concentration of reducing sugar.

Red or Change colour (Benedict's)

An observation in the Benedict test indicating a high concentration of reducing sugar.