Mastering Chemistry Help

Perfumes Perfumes are the materials which give fragrance. A good perfume should have three essential ingredients. They are 1. Vehicle or Solvent 2. Fixative 3. Odorous substance 1. Vehicle or Solvent The vehicle or Solvent is used to keep the odour producing substances in solution. Ethanol and water mixture is most commonly used in perfumery. 2. Fixative Fixative regulate the evaporation of various odoriferous components of perfumes. Sandal wood oil, Benzoin, glyceryl diacetate and esters of cinnamyl alcohols are used as fixative. 3. Odorous Substance The function of odorous substance is to provide pleasant fragrance to perfume. Odorous substances may be natural or synthetic. Terpenoids like linalool is a natural odoriferous substance. Anisaldehyde (p-methoxy benzaldehyde) is an example for synthetic odoriferous substance. Related posts Chemicals in Food

Pottassium Permanganate ( KMnO 4 ) is prepared from Pyrolusite ore ( MnO 2 ). The finely powdered Pyrolusite ore ( MnO 2 ) is fused with an alkali metal hydroxide like KOH in the presence of air or an oxidizing agent like KNO 3 to give the dark green potassium Manganate ( K 2 MnO 4 ). Potassium manganate disproportionate in a neutral or acidic solution to give potassium permanganate . 2 MnO 2 + 4 KOH + O 2 ----------> 2K 2 MnO 4 + 2H 2 O 3 MnO 4 2- + 4H + ------------> 2MnO 4 - + MnO 2 + 2H 2 O Commercially potassium permanganate is prepared by the alkaline oxidative fusion of Pyrolusite ore ( MnO 2 ) followed by the electrolytic oxidation of manganate (4) ion . 2 MnO 2 + 4KOH + O 2 -----------> 2 K 2 MnO 4 + 2H 2 O MnO 4 2- ------( electrolytic oxidation )----> MnO 4 - + e - Properties Potassium permanganate forms dark purple (almost black) crystals , which are iso structural with those of KCLO 4 . It has weak temperature dependent...

Preparation of Potassium dichromate ( K 2 Cr 2 O 7 ) Potassium dichromate (K 2 Cr 2 O 7 ) is prepared from chromite ore FeCr 2 O 4 . The chromite ore is fused with sodium or potassium carbonate in free access of air. 4FeCr 2 O 4 + 8Na 2 CO 3 + 7O 2 -------> 8Na 2 CrO 4 + 2FeO 3 + 8CO 2 The yellow solution of sodium chromate is filtered and acidified with sulfuric acid to give a solution from which orange sodium dichromate , Na2Cr2O7 2H2O can be crystallized. 2Na 2 CrO 4 + 2H + ---------> Na 2 Cr 2 O 7 + 2Na + + H 2 O Sodium dichromate is more soluble than potassium dichromate. Hence sodium dichromate when fused with KCl forms orange crystals of potassium dichromate. Na 2 Cr 2 O 7 + 2KCl --------> K 2 Cr 2 O 7 + 2NaCl The chromates and dichromates can be inter convertible. 2CrO 4 2- + 2H 2+ ---------> Cr 2 O 7 2- + H 2 O Cr 2 O 7 2- + 2OH- ---------> 2CrO 4 2- + H 2 O The dichromate ion and chromate ion exist in equilibrium with each other at a pH of ...

Concentration Beneficiation by Forth flotation This method is used for the concentration of sulphide ores which are lighter than the impurities. The powdered ore is added to water containing pine oil (frothing agent) and sodium ethyl xanthate (collecting agent). The mixture is strongly agitated by passing compressed air. The sulphide particles stick to the oil droplets forming a forth which rises to the surface. The heavier gangue particles settle to the bottom of the vessel. The forth is skimmed off and heated to separate the oil and the sulphide. Related post Leaching: metallurgy