Titration - Volumetric analysis
The procedure of addition of the known solution from the burette to the measured volume of solution of the substance to be calculated until the reaction among the two is just done, is termed as titration. So, a titration involves two solutions;
(i) Unknown solution : The solution contains the substance to be estimated is termed unknown solution. The substance is known as titrate.
(ii) Standard solution : The solution where an accurately known amount of the reagent (titrant) has been dissolved in a known volume of the solution is termed standard solution. There are two kinds of reagents (titrants) :
(a) Primary standards: These can be precisely weighed and their solutions are not to be standardised previous to make use of. Oxalic acid (H2C2O4.2H2O), potassium dichromate (K2Cr2O7), silver nitrate (AgNO3), copper sulphate (CuSO4.5H2O), ferrous ammonium sulphate that is FeSO4(NH4)2SO2.6H2O, sodium thiosulphate that is Na2S2O3.5H2O, etc., are the instances of primary standards.
(b) Secondary standards : The solutions of these reagents are to be standardised before use as these cannot be weighed accurately. The examples are potassium hydroxide (KOH), sodium hydroxide (NaOH), hydrochloric acid (HCl), potassium permanganate (KMnO4), iodine, sulphuric acid (H2SO4)etc.