Question

Sodium tripolyphosphate is used in detergents to make them effective in hard water. calculate the oxidation number of phosphorus in na5p3o10. assume that all the phosphorus atoms have the same oxidation number.

Answer 1

Step 1:
           Write molecular Formula,

                                                Na₅P₃O₁₀
Step 2:
          Assign Oxidation number to Na (which is +1) and O (which is -2), and X (unknown) for P.
                                               (+1)₅ + (X)₃ + (-2)₁₀  = 0

Zero means overall charge on molecule is zero (Neutral).

Step 3:
           Now solve for X,
                                               (+5) + (X ÷ 3) + (-20)  =  0

                                                X ÷ 3  =  -5 + 20
                                
                                                X ÷ 3  =  +15

                                                      X  =  +15 ÷ 3

                                                      X  =  +5

Result:
           Oxidation number of P is +5.