Question

What is the oxidation state of Phosphorus in \(H_3PO_4\)?

• A. \(+3\)
• B. \(+5\)
• C. \(+1\)
• D. \(-3\)

Hint:

To quickly find oxidation states in oxyacids, remember that hydrogen contributes \(+1\) and oxygen contributes \(-2\). Set the sum equal to zero for neutral molecules and solve for the unknown element.

Answer 1

The Correct Option is B

Concept: The oxidation state of an element represents the hypothetical charge that an atom would have if all bonds were completely ionic. To determine the oxidation state, we use the following rules:
• Hydrogen usually has oxidation state \(+1\).
• Oxygen usually has oxidation state \(-2\).
• The sum of oxidation states of all atoms in a neutral molecule is \(0\).

Step 1: Assign oxidation states to known elements. For the molecule \(H_3PO_4\): \[ H = +1, \quad O = -2 \] Let the oxidation state of phosphorus be \(x\).

Step 2: Form the oxidation state equation. \[ 3(+1) + x + 4(-2) = 0 \] \[ 3 + x - 8 = 0 \] \[ x - 5 = 0 \] \[ x = +5 \] Thus, the oxidation state of phosphorus is \[ \boxed{+5} \]