CHEM ACT 11

• Carbonyl Carbon atom


  Attached to 2 hydrogen atoms or a hydrogen atom and a carbon atom
• Carbonyl Carbon atom


  Attached to 2 carbon atoms
• Carbonyl Carbon atom


  Attached to an OH group and a carbon atom
• Miscible


  Presence of 1 layer
• Immiscible


  • Presence of 2 layers
  • Insoluble or limited solubility
• Carbonyl compounds


  • Highly polar due to a more electronegative oxygen atom present in the carbonyl group
  • Short chains are soluble in water
  • Soluble in organic solvent
  • Less dense than water allows interaction with each other through dipole-dipole interactions
  • Lower aldehydes and ketones can form hydrogen bonds with water

  
• Total acidity


  • Measures total acid concentration
  • A measure of concentrations of hydrogen ions
  • Amount of base required to neutralize the acid/s in a sample
• pH


  Measures how strong or weak acids are (how acidic or alkaline the samples are)
• Titratable acids


  • Indicate the amount of acid present (does not necessarily equate to concentration of hydrogen ion)
  • A more accurate and more preferred way to measure perceived sourness
• Citric acid


  • Weak acid (pH 3 to 6)
  • Organic compound found in citrus fruits
  • Odorless, sour in taste, and appears as a white crystalline solid
• Titration of fruit samples


  Add NaOH (base) until blue litmus paper remains blue
• Fruit ripening


  • Titratable acids decrease
  • pH increase
  • Starch hydrolyzed to sweet monosaccharides
  • Accumulation of sugars leading to sweet taste
• Reducing sugars and non-reducing sugars

  Estimation or detection
• Benedict's test


  1. Tartrate ions prevent the formation of insoluble Cu(OH)2

  2. Bistartarocuprate (II) complex oxidizes aldehydes to carboxylic acid

  3. Cupric ions reduced to Cuprous ions forming insoluble Cu2O (red precipitate)
• Positive Benedict's test


  • Presence of yellow or red brick precipitate
  • Indicates presence of aldehydes or reducing sugars
• Positive Tollen's test


  • Dark grey precipitate or silver mirror
  • Metal ions as an oxidizing agent
  • Reduction of silver ion to metallic silver
• Positive Fehling's test


  • Presence of brick red precipitate
  • Metal ion as an oxidizing agent
  • Cupric ions reduced to cuprous ions
• Oxidation of ketones


  1. Under extreme conditions with strong oxidizing agent (KMnO4)

  2. C-C cleavage occurs leading to formation of 2 carboxylic acids