Determine the oxidation state of phosphorus in the pyrophosphate ion P2O74-: - +3.5 - +5 - +7 - +10 - VCE - SSCE Chemistry - Question 19 - 2012 - Paper 1

To find the oxidation state of phosphorus in the pyrophosphate ion ext{P}_2 ext{O}_7^{4-}$, we start by recognizing the structure of the ion.

1. Identify the Components: The pyrophosphate ion consists of two phosphorus atoms and seven oxygen atoms.

2. Assign Oxidation States to Oxygen: We assign the oxidation state of oxygen as ext{-2}. Thus, for seven oxygen atoms, the total contribution will be: $ext{Total oxidation state from oxygen} = 7 imes (-2) = -14$

3. Set Up the Equation: Let the oxidation state of phosphorus be denoted as $x$. For the pyrophosphate ion, the overall charge is ext{-4}: $2x + (-14) = -4$

4. Solve for x: Rearranging the equation gives:

   2x = 10 \ x = 5$$

Thus, the oxidation state of phosphorus in ext{P}_2 ext{O}_7^{4-} is +5.