17 Questions
What is the main purpose of the Iodoform Test?
To identify the presence of acetone
Which substance is NOT a product of the Iodoform Test?
4NaOH
What happens when acetone reacts in the Iodoform Test?
It produces CH₃COONa
Which reactant is essential for the formation of iodoform in the Iodoform Test?
CH₃COCH₃
What is the role of iodine solution in the Iodoform Test?
To produce NaI
What is the product formed when benzaldehyde undergoes auto-oxidation?
Benzoic acid
In Fehling’s test, which compound exhibits a reaction resulting in a brick red precipitate?
Formaldehyde
What happens when acetone is mixed with Fehling’s solution?
Remains blue
Which compound forms acetone bisulfate upon addition of sodium bisulfate?
Acetone
What is the product formed when phenylhydrazone is created from acetone and 2,4-dinitrophenylhydrazine?
2,4-dinitrophenylhydrazone
Which compound, when exposed to formalin, turns into jelly?
Gelatin
What is the product formed when copper reacts with oxygen?
Copper oxide
In the Silver Mirror Test, what is the significance of observing a silver mirror on the walls of the test tube?
Indication of presence of formaldehyde or benzaldehyde
Which substance is involved in the Resorcinol Test along with formaldehyde and sulfuric acid?
Resorcinol solution
What color change is observed when Schiff's solution reacts with benzaldehyde?
Magenta
Which reaction does not result in the formation of a product in the given experiment?
Cu + HCHO + HOH → CuO + CH₃OH
What is the name of the test used to identify the presence of formaldehyde based on a color change to pink?
Schiff's Test
Study Notes
Iodoform Test
- Reactants: acetone (CH₃COCH₃), 10% sodium hydroxide (NaOH), and iodine solution
- Products: CH₃COONa, NaI, iodoform (CHI₃ ↓), and 5H₂O
- Equation: CH₃COCH₃ + 4NaOH + 3I₂ → CH₃COONa + 3NaI + CHI₃ ↓ + 3H₂O
- Formation of yellow ppt (CHI₃ ↓)
Acetone Reaction with Ammoniacal Solution of Silver Nitrate
- Reactants: acetone (CH₃COCH₃) and ammoniacal solution of silver nitrate (Ag(NH₃)₂OH)
- No reaction
Fehling's Test
- Reactants: Fehling's solution (Cu(OH)₂) and formalin (HCHO)
- Products: formic acid (HCOOH), copper oxide (Cu₂O↓), and H₂O
- Equation: HCHO + Cu(OH)₂ → HCOOH + Cu₂O ↓ + H₂O
- Formation of brick red ppt (Cu₂O↓)
Benzaldehyde Reaction with Fehling's Solution
- Reactants: Fehling's solution (Cu(OH)₂) and benzaldehyde (C₆H₅CHO)
- No reaction; remained blue
Acetone Reaction with Fehling's Solution
- Reactants: Fehling's solution (Cu(OH)₂) and acetone (CH₃COCH₃)
- No reaction; remained blue
Auto-Oxidation of Benzaldehyde
- Reactants: benzaldehyde (C₆H₅CHO) and O₂
- Products: benzoic acid (C₆H₅COOH)
- Equation: C₆H₅CHO + O₂ → 2C₆H₅COOH
- Formation of white crystalline ppt (C₆H₅COOH)
Addition of Sodium Bisulfate to Acetone
- Reactants: sodium bisulfate (NaHSO₃) and acetone (CH₃COCH₃)
- Products: acetone bisulfate (CH₃C(OH)(SO₃Na)CH₃)
- Equation: NaHSO₃ + CH₃COCH₃ → CH₃C(OH)(SO₃Na)CH₃
- Formation of white crystal ppt
Formation of Phenylhydrazone
- Reactants: acetone (CH₃COCH₃) and 2,4-dinitrophenylhydrazine (C₆H₃(NO₂)₂NHNH₂)
- Products: 2,4-dinitrophenylhydrazone
Experiment 5: Formaldehyde and Aromatic Aldehyde
Preparation of Formaldehyde from Methanol
- Reactants: copper spiral (Cu), methyl alcohol (CH₃OH)
- Products: Cu, formaldehyde aka methanal (HCHO), and H₂O
- Equation: 2Cu + O₂ → 2CuO, CuO + CH₃OH → Cu + HCHO + HOH
Schiff's Test
- Reactants: Schiff's solution and formaldehyde (HCHO)
- Solution turned pink
- Reactants: Schiff's solution and benzaldehyde (C₆H₅CHO)
- Formation of magenta color of fuchsin
- Reactants: Schiff's solution and acetone (CH₃COCH₃)
- No reaction
Resorcinol Test
- Reactants: resorcinol solution (C₆H₆O₂), formaldehyde (HCHO), and conc.sulfuric acid (H₂SO₄)
- Red flocculent layer is found at the junction of two layers (pink/magenta)
- Mother layer is colorless
Silver Mirror Test or Tollen's Test
- Reactants: ammoniacal solution of silver nitrate (Ag(NH₃)₂OH) and formalin (HCHO)
- Products: ammonium formate (HCOONH₄), ammonia gas (NH₃), Ag (s), and H₂O
- Equation: HCHO + 2Ag(NH₃)₂OH → HCOONH₄ + 3NH₃ + 2Ag (s) + HOH
- Formation of silver mirror on walls of test tube
- Reactants: ammoniacal solution of silver nitrate (Ag(NH₃)₂OH) and benzaldehyde (C₆H₅CHO)
- Products: ammonium benzoate (C₆H₅COONH₄), NH₃, Ag (s), and H₂O
- Equation: C₆H₅CHO + 2Ag(NH₃)₂OH → C₆H₅COONH₄ + 3NH₃ + 2Ag (s) + HOH
- Formation of silver mirror
Learn about the process, materials involved, observations, and reactions in the preparation of formaldehyde from methanol. Understand the use of Schiff’s Test for detecting formaldehyde and benzaldehyde, along with their characteristic color changes.
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