Question

When making/doing calculations for phosphate buffer solution why is the "suffix" hydrate not written at the end for the salts but the molar mass of the waters are still included in the calculation?

For example, its written as Disodium hydrogen phosphate in the materials but 6H2O is not included at the end of the formula but we still include the molar masses of the water molecules in the calculation.

Answer 1

Since Disodium hydrogen phosphate exist in form of hexahydrated salt it is not written in the formula but while doing calculation we consider it , this problem is related with basic stoichiometry.

suppose we has x gm Na2HPO4.6H2O , to calculate moles we have to consider molar mass of complete hexahydrate salt , if we take only Na2HPO4 moles calculated will be greater than actual moles and will be erroneous.