Question

I know that pyrophosphite by itself

is (P2O5)4−..My question is
about the hydrogen part- how to know how
many hydrogens to add? The answer key for
this question says the compound
is KH3P2O implying that I
should add 3 hydrogens. But why not add 1
hydrogen and have K3 instead?

Answer 1

To determine the number of hydrogens to add to pyrophosphite (P2O5)4−, we consider the compound's charge and the valency of potassium. The compound KH3P2O indicates that 3 hydrogen atoms are attached to the phosphorous atom, balancing the charges.

Step-by-step explanation:

In this case, to determine how many hydrogens to add to pyrophosphite (P2O5)4−, we have to consider the charge of the compound and the valency of potassium (K+).

The compound KH3P2O indicates that there are 3 hydrogen atoms attached to the phosphorous atom.

The valency of potassium is +1. Therefore, to balance the charges, we need to add 3 hydrogen atoms.

If only 1 hydrogen atom was attached, the compound would be K3PO, which would not correctly balance the charges.