How to convert P2O5 concentration to H3PO4 concentration?
P X 2 O X 5 content is useful as it is the phosphorous content that a scientist often cares about when using phosphoric acids. This might seem silly given that as you pointed out anything from 0 − 70 % P X 2 O X 5 could just be expressed as a percentage of H X 3 P O X 4 but there are times when a higher P X 2 O X 5 concentration is desired.
Phosphorus Pentoxide (P2O5)
Phosphorus pentoxide is a white solid which does not have any distinct odour. The chemical formula of this compound is P 4 O 10. However, it is named after its empirical formula, which is P 2 O 5. The molar mass of phosphorus pentoxide corresponds to 283.9 g/mol. The density of this solid is 2.39 g/cm 3. The melting point of this P 2 O 5 is 613K.