POST LAB

• Most non-polar molecules are water-insoluble or hydrophobic at room temperature.
• polar molecule generally has a higher boiling point, because ofthe dipole-dipole interaction between their molecules
• fats are non polar and water is polar
• fats (non-polar) are generally soluble in organic solvents andlargely insoluble in water (polar)
• Lipids with high hydrocarbon content are relatively nonpolar innature and insoluble in water.
• like dissolves like
• Lipids containing charged groups can be dissolved in water.
• Lipids that are derived from glycerol and sphingosine will produce translucent “spots” / “stains” on fabric.
• Test for Unsaturation of Fatty Acids: the red bromine color of the reagent (Br water in CCl4) is discharged when the unsaturated function reacts with the bromine
• The more double bonds a fat contains, the more iodine required for the addition reaction; thus, a high iodine number means a high degree of unsaturation.
• the Reddy brown color of iodine turns colorless
• animal fats are saturated and vegetable fats are unsaturated with some exceptions.
• Acrolein Test


  test for the presence of glycerin or fats
• Rancidity


  aerial oxidation of unsaturated fat marked by unpleasant odour or flavour
• Rancidity is the decomposition of fats, oils and other lipids by hydrolysis or oxidation
• coconut oil is slow to oxidize and thus resistant to rancidity, lasting up to two years due to its high saturated fat content.
• Biuret Test


  used for detecting the presence of peptide bonds
• violet color indicates the presence of proteins
• Dipeptides yield a negative result.
• Millon's Reaction


  is given by any compound containing a phenolic hydroxy group.
• Millon's reaction will give a positive test of a pink to dark-red color.
• Tyrosine is the only amino acid found in proteins having a phenolic group
• Xanthoproteic Reaction


  Proteins when treated with concentrated HNO3 turn yellow and change to orange when neutralized with NaOH.
• Xanthoproteic Reaction: Proteins when treatedwith concentrated HNO3 turn yellow and change to orange when neutralized with NaOH.
• Test for Sulfur


  tp produce a black precipitate of lead sulfide
• test for sulfur produces a black precipitate of lead sulfide
• Hopkin's cole reaction form a violet cyclic product. it only reacts with proteins containing tryptophan.
• Hopkin's cole reaction form a violet cyclic product. it only reacts with proteins containing tryptophan.
• Ninhydrin Test


  produce a blue-purple product when protein is boiled
• Ninhydrin Test produces a blue-purple product when protein is boiled
• Ninhydrin Test produces a blue-purple product when protein is boiled
• Heavy metal salts 


  act to denature proteins in much the same manner as acids and bases
• Salts of heavy metals results in white precipitation
• Salts of heavy metals is used for its disinfectant properties in external applications.
• Salts of Heavy Metals

  For example AgNO3 is used to prevent gonorrhea infections in the eyes of new born infants. Silver nitrate is also used in the treatment of nose and throat infections, as well as to cauterize wounds.
• ALKALOIDAL REAGENTS


  Tannic and picric acids are used for treating burns because they produce astringent effect on the tissues, diminish secretion of mucous membranes and prevent absorption of toxins.
• Tannic and picric acids are used for treating burns because they produce astringent effect on the tissues, diminish secretion of mucous membranes and prevent absorption of toxins.
• In alkaloidal reagents, formation of precipitation indicates the presence of proteins
• Inorganic acids precipitate in protein
• HNO3 is used for detecting the presence of proteins in the urine