Question

The oxidation number of phosphorus in pyrophosphoric acid is

• A. +3
• B. +1
• C. +4
• D. +5

Answer 1

The Correct Option is D

 To determine the oxidation number of phosphorus in pyrophosphoric acid, we need to understand the chemical structure and composition of the compound. Pyrophosphoric acid has the chemical formula \(H_4P_2O_7\).

1. Break down the formula: The formula consists of 4 hydrogen atoms, 2 phosphorus atoms, and 7 oxygen atoms.
2. Understanding oxidation numbers:
   • Hydrogen generally has an oxidation number of +1.
   • Oxygen generally has an oxidation number of -2.
3. Calculate the total oxidation contribution by hydrogen and oxygen:
   • Total contribution from hydrogen: \(4 \times (+1) = +4\)
   • Total contribution from oxygen: \(7 \times (-2) = -14\)
4. Use the charge balance equation for the molecule \(H_4P_2O_7\):

4 \times 1 + 2 \times x + 7 \times (-2) = 0

1. Simplify and solve for \(x\) (the oxidation number of phosphorus):

4 + 2x - 14 = 0 \ 2x - 10 = 0 \ 2x = 10 \ x = +5

1. Conclusion: The oxidation number of phosphorus in pyrophosphoric acid is \(+5\). This confirms that the correct answer is

+5

1. .

Therefore, the correct oxidation number of phosphorus in pyrophosphoric acid is option

+5

.