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CHEM LAB

CHEM LAB. Exam Tips 2.ppt. SODIUM FUSION(LASSAIGNES) TEST. THE ORGANIC COMPOUND TO BE TESTED IS FUSED WITH METALLIC SODIUM.IN THIS WAY SODIUM CYANIDE,SODIUM SULPHIDE AND/OR SODIUM HALIDES IS FORMED WHICH CAN BE READILY IDENTIFIED. TEST FOR NITROGEN.

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CHEM LAB

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  1. CHEM LAB Exam Tips 2.ppt

  2. SODIUM FUSION(LASSAIGNES) TEST • THE ORGANIC COMPOUND TO BE TESTED IS FUSED WITH METALLIC SODIUM.IN THIS WAY SODIUM CYANIDE,SODIUM SULPHIDE AND/OR SODIUM HALIDES IS FORMED WHICH CAN BE READILY IDENTIFIED.

  3. TEST FOR NITROGEN • THE CYANIDE FORMED CAN BE DETECTED BY PRUSSIAN BLUE TEST. • STEP 1: FESO4 + 6NACN=Na4[Fe(CN)6]+Na2SO4 • STEP 2: 3Na4[Fe(CN)6] + 2Fe2(SO4)3=Fe4[Fe(CN)6]3(PRUSSIAN BLUE)+6Na2SO4

  4. TEST FOR SULPHUR • THIS IS TESTED AS SULPHIDE • TEST 1: THE COMPOUND IS TREATED WITH DIL. ACETIC ACID AND THEN WITH LEAD ACETATE. A BLACK PRECEPATE OF LEAD ACETATE INDICATES THE PRESENCE OF SULPHUR TEST 2: THE COMPOPUND IS TREATED WITH DIL.SOLN. OF Na2[Fe(CN)5NO] A PURPLE COLOURED COMP. OF Na4[Fe(CN)5NOS] IS FORMED INDICATING THE PRESENCE OF SULPHUR.

  5. TEST FOR HALOGENS • THE FUSION SOLN IS ACIDIFIED WITH DIL.HNO3 AND THEN EXCESS OF AgNO3 IS ADDED.

  6. _OH (ALCOHOLIC) • TEST 1::SODIUM TEST • 2ROH+2Na=2RONa+H2(GAS) • TEST 2:: ACETYL CHLORIDE TEST acetyl chloride reacts vigorously with primary and secondary alcohols with evolution of HCl. HCl +NH4OH =NH4Cl(WHITE FUMES)+ H2O

  7. PHENOL • GIVES VIOLET COLOUR WITH FeCl3 SOLN. FeCl3+6C6H5OH= [Fe(OC6H5)6]-3+3HCl

  8. CARBONYL TEST • FOR ALDEHYDES AND KETONES. 2,4-DINITROPHENYL HYDRAZINE-TEST -> FORMATION OF CRYSTALLINE PRECIPITATE WITH THE REAGENT INDICATES THE PRESENCE OF ALDEHYDES AND KETONES.

  9. SPECIFIC FOR ALDEHYDES • SCHIFF’S TEST ->APPEARANCE OF PINK RED OR MAGENTA COLOR WITH REAGENT. TOLLEN’S TEST ->SILVER MIRROR WITH REAGENT(Ag+). FEHLING’S TEST ->RED PRECIPITATE OF Cu2O WITH ALDEHYDE GROUP.

  10. CARBOXYLIC GROUP • LITMUS TEST (BLUE TO RED). • SODIUM BICARBONATE TEST(NaHCO3).CO2 MOVES OUT FROM NaHCO3. • ESTER TEST: REACTS WITH ALCOHOL TO GIVE SWEET SMELLING COMPOUND(ESTER).

  11. ALIPHATIC AMINO GROUP • WITH HNO2 PRIMARY GROUP GIVES ALCOHOL • WITH HNO2 SEC GIVES NITROSOAMINES YELLOW OILY LIQUID(R2N-NO). • WITH HNO2 TERTIARY GROUP GIVES TRIALKYLAMMONIUM NITRITE (R3 N+ HONO-)

  12. AROMATIC AMINES • WITH HNO2 PRIMARY GIVES BENZENE DIAZONIUM CHLORIDES(PhN2+ Cl-). • SECONDARY GROUP GIVES N-ALKYL-N-PHENYL NITROSOAMINE. • TERTIARY GROUP GIVES P-NITROSOANILINE.

  13. SPECIFIC FOR PRIMARY AMINE(ALI+ARO) UNPLEASANT ODOUR OF ISOCYNIDE(RNC) WITH CHLOROFORM+KOH.

  14. NITRO GROUP • THE PRESENCE OF NITRO GROUP CAN BE DETYECTED BY REDUCING THE COMPOUND WITH Sn/HCl AND THEN CONDUCTING CARBYL AMINE TEST.

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