CH31 EX10 PRELAB PDF

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Juan Carlos Michelena 10 / 7 / 2014 KD Marquez. Gel Dalangin Ma’am Bonifacio EX10: ALDEHYDES and KETONES I. OBJECTIVE Observe reactivities of several aldehydes and ketones through qualitative analysis. II. PROCEDURE A. Reaction with 2,40dinitrophenylhydrazine (2,4-DNPH) Record the color of the Placw...

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Juan Carlos Michelena

10 / 7 / 2014

KD Marquez. Gel Dalangin

Ma’am Bonifacio EX10: ALDEHYDES and KETONES

I.

OBJECTIVE Observe reactivities of several aldehydes and ketones through qualitative analysis.

II.

PROCEDURE A. Reaction with 2,40dinitrophenylhydrazine (2,4-DNPH) Placw 5 drops of 95% CH3CH2OH in three separate micro test tubes

To one test tube, add 2 drops of acetone and to the other one, add 2 drops of benzaldehyde

Record the color of the precipitate formed. If no precipitate forms immediately, let stand for a few minutes

To each of the three test tubes, add 1 mL 2,4-DNPH in HCl solution

B. Schiff’s Test Place 4 drops of Schiff's reagent in 3 separate micro test tubes

To one test tube, add 1 drop of formalin; to the second test tube, add 1 drop of acetone; and to the third test tube, add 1 drop of benzaldehyde

Shake and record the color that develops within 3-4 minutes

C. Benedict’s Test Place 5 drops of Benedict's reagent in 2 separate micro test tubes

To one test tube, add 2 drops of formalin and to the other test tube, add 2 drops of benzaldehyde

Place the test tubes in hot water bath. Note the formation of brick red precipitate

D. Iodoform Test Place 5 drops of 10% NaOH in 2 separate test tubes

Warm the solution in a water bath

To one test tube, add 2 drops of acetone and to the other test tube, add 2 drops of 95% CH3CH2OH

If the solution becomes colorless after heating, add more I2 in KI solution and take note if the solution turns yellow again

Into each mixture, add I2 in KI solution until the solution becomes pale yellow

Record the color of the solution after each addition of I2 in KI before and after heating

E. Effect of Acid Concentration on the Rate of Addition of 2,4-Dinitrophenylhydrazine Weigh 0.15 g 2,4dinitrophenylhydrazine in a beaker and dissolve in 15 mL acetone

Decant if there are undissolved solids

To one test tube, add 1 drop 0.1 M CH3COOH; to the second test tube, add 1 drop 0.1 M HCl; and to the third test tube, add 1 drop 1.0 M HCl

Place 5 drops of the previously prepared 2,4-dinitrophenylhydrazine solution into 4 different micro test tubes. Keep one test tube as standard

Note the time of mixing and the time when crystlas appear

III.

MSDS Reagent/Product

Structure

Physical Prop.

Hazards

Formalin

CH2O

Colorless Liquid BP: 64.5 C MP: -97.8 C

Skin: slightly hazardous (sensitizer).

2,4dinitrophenylhydra zine

C6H6N4O4

Solid MP: 200 C

Very hazardous in case of ingestion, inhalation, skin and eye contact.

Colorless liquid *Oxidizes aldehydes to acids; during reaction the silver, bound in a complex, is reduced to metallic silver and forms a silver mirror. Colorless liquid BP: 100 C

Prepare freshly! Old, opaque or "dried out" solutions are explosive

Liquid BP: 100 C

Very hazardous. May produce burns. Inhalation may produce severe irritation of respiratory tract, characterized by coughing, choking, or shortness of breath Very hazardous in case of ingestion, inhalation, skin and eye contact.

Tollens’ reagent Composed of -silver nitrate -sodium hydroxide -ammonium hydroxide.

Schiff’s reagent Composed of -sodium metabisulfite -hydrogen chloride -hydrogen oxide -basic fuchsin Benedict’s reagent Composed of -sodium citrate dihydrate -sodium carbonate -copper sulfate pentahydrate -hydrogen oxide

Sodium hydroxide

NaOH

[Na]+ + [OH]-

Odorless white solid MP: 323 C BP: 1388 C

Waste

Very hazardous in case of ingestion, inhalation, skin and eye contact.

INORGANIC

Acetic Acid

C2H4O2

MP: 16.7 C BP: 118 C

Strongly corrosive and causes serious burns. Very harmful if swallowed.

Hydrochloric Acid

HCl

Clear-yellow liquid w/ pungent odor MP: -25 C BP: 109 C

Corrosive. Fatal Ingestion. Liquid can cause severe eye/skin damage.

[H]+ + [Cl]-

Ethanol

C2H5OH

Colorless liquid Mild odor MP: -114.1 C BP: 78 C

Severe eye and skin irritation; nausea, vomiting and diarrhea

Iodine

I2

Purple to black crystals MP: 114 C BP: 183 C Specific gravity: 4.93 Solid BP: 1330 C MP: 681 C

Toxic - may be fatal if swallowed or inhaled. Causes burns. Harmful by inhalation and skin absorption. Hazardous in case of ingestion, inhalation, skin and eye contact.

I–I

Potassium Iodide

KI [K]+ + [I]-

Acetone

(CH3)2CO

Colorless liquid Fragrant, sweet odor MP: -95 C BP: 56 C

Hazardous in case of ingestion, inhalation, skin and eye contact.

Benzaldehyde

C6H5CHO

Colorless to yellow liquid Almond-like odor MP: -26 C BP: 179 C

Irritant in case of ingestion, inhalation, skin and eye contact.

HALOGENATED...