Chemical Analysis Chemical analysis is divided into two main classes: І - Qualitative Analysis: This type of analysis involves the investigation and identification of substances in its simplest or complicated forms.

ІІ- Quantitative Analysis: The object of quantitative analysis is to determine the actual amounts of the constituents of a compound, and also the amount of material dissolved in solutions. a) Volumetric analysis : i.e., determination of the constituents by titration. b) Gravimetric analysis : i.e., determination of the constituents by pptn. c) Instrumental analysis : i.e., determination of the constituents by the use of instruments

Inorganic Qualitative Analysis When an acid, e.g. HCl is made to react with a base, e.g. NaOH, salt, NaCl, and water are formed according to the following equation : HCl + NaOH = NaCl + H 2 O acid base salt water The part of the salt which is derived from the base, Na +, is called the" basic radical",where as the other part which is derived from the acid is termed the" acidic radical".

Part І: Identification of Anions The common anions are devided into three groups I- Those which evolve gases with dilute hydrochloric acid : 1- Carbonate (CO 3 2- ) 2- Bicarbonate(HCO 3 - ) 3- Nitrite(NO 2 - ) 4- Sulphite(SO 3 2- ) 5- Thiosulphate(S 2 O 3 2- ) 6- Sulphide (S 2- )

II- Those which do not react with dilute HCl, but which do evolve gases or volatile liquids with concentrated: 1- sulphuric acid: 2- Chloride (Cl - ) 3- Bromide (Br - ) 4- Iodide (I - ) 5- Nitrate (NO 3- )

III- Those which do not react with either dilute hydrochloric acid or concentrated sulphuric acid: 1- Phosphate (PO 4 3- ) 2- Borate (B 4 O 7 2- ) 3- Sulphate (SO 4 2- )

I- Anions which react with dilute hydrochloric acid Carbonates (CO 3 2- ) All carbonates except those of alkali metals, and ammonium are very slightly or difficulty soluble in water.Accordingly reactions in solution are only carried out in case of the soluble salts. Effervescence and a colourless odourless gas is evolved, Carbon dioxide(CO 2 ), Na 2 CO 3 + 2HCl  2NaCl + H 2 O+ CO 2 Solid salt + dil. HCl

Reddish brown precipitate of mercuric carbonate Na 2 CO 3 + HgCl 2  HgCO 3 ↓+2NaCl Salt solution + mercuric chloride solution

II- Anions which react with concentrated sulphuric acid Chlorides (Cl - ) All chlorides are water soluble except the chlorides of silver, mercurous and cuprous. Effervescence with evolution of colourless gas, Hydrogen chloride (HCl), 2NaCl + H 2 SO 4  Na 2 SO 4 +2 HCl Test for HCl gas: Dip a clean glass rod into a bottle of conc. ammonia solution, and hold it close to the mouth of the test tube in which the HCl is being produced. Dense white fumes of ammonium chloride will be formed: HCl +NH 3  NH 4 Cl Solid salt + conc.H 2 SO 4 :

A white ppt. of lead sulphite (PbSO 3 ) is formed. Na 2 SO 3 + Pb(CH 3 COO) 2  PbSO 3 ↓+ 2 CH 3 COONa ppt Salt solution + lead acetate solution Pb(CH 3 COO) 2 * Salt solution + drops of acidified solution of KMnO 4 : The purple colour of the permanganate will disappear. The sulphite reduces the permanganate ion to (Mn 2+ ) which is almost colourless. 5Na 2 SO 3 +2KMnO 4 +3H 2 SO 4  5Na 2 SO 4 +K 2 SO 4 +2MnSO 4 +3H 2 O

III- Anions which do not react with acids: Sulphates (SO 4 2- ) All sulphates are soluble in water except those of some divalent metals e.g. calcium, strontium, barium and lead. A white precipitate of barium sulphate (BaSO 4 ) is formed which is insoluble in dilute acids and in excess of barium chloride. Na 2 SO 4 + BaCl 2  BaSO 4 ↓+ 2NaCl Salt solution + Barium chloride solution (BaCl 2 )

For sulphates: Salt solution + lead acetate: A white precipitate of lead sulphate is formed, which is redadly soluble in hot concentrated ammonium acetate or conc.H 2 SO 4 K 2 SO 4 +Pb(CH 3 COO) 2  PbSO 4 ↓ +2CH 3 COOK PbSO 4 + H 2 SO 4  Pb(HSO 4 ) 2