Sodium Thiosulphate Standard Solution 0.01 N (0.01 M) is a secondary standard volumetric solution commonly used in analytical chemistry for titration, specifically in iodometric reactions to determine the concentration of oxidizing agents. Concentration Equality for sodium thiosulphate (Na2S2O3), the Molarity (M) equals Normality (N) because the equivalent weight is equal to the molecular weight (n=1 in most redox titrations). Because it is not a primary standard, it must be standardized against a primary standard like potassium iodate (KIO3) or potassium dichromate (K2Cr2O7) using a starch indicator.