What is the oxidation number of NaH2PO4?

1 Answer

The overall charge of NaH2PO4 is zero.

Explanation:

However, only each atom in the compound has its own oxidation number.

Here are the rules you use to calculate them:

  1. The oxidation number of a Group 1 metal in a compound is +1.
  2. The oxidation number of H in a compound is usually +1.
  3. The oxidation number of O in a compound is usually –2.
  4. The sum of all oxidation numbers in a neutral compound is zero.

We can use these rules to calculate the oxidation numbers of the atoms in the compound.

Thus, the oxidation numbers of Na, H, and O are +1, +1, and -2 (Rules 1, 2, and 3):

+1Na+1H2P-2O4

We can use Rule 4 to calculate the oxidation number of P.

I will write the total oxidation numbers of each atom below the formula.

+1Na+1H2P-2O4
+1Na+2H2P-8O4

We know from Rule 4 that the sum of all the oxidation numbers must equal zero.

The sum of all the oxidation numbers showing is +1+28=-5.

Thus, the oxidation number of P must be +5.

+1Na+1H2+5P-2O4
+1Na+2H2+5P-8O4