Question

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

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

Hint:

To find oxidation states quickly, remember common values: Hydrogen \(+1\), Oxygen \(-2\), Alkali metals \(+1\), and the total oxidation number of a neutral compound is always zero.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The objective is to determine the oxidation number of Phosphorus (P) in Phosphoric acid (\(H_3PO_4\)) using the rules of oxidation states.
Step 2: Key Formula or Approach:
The sum of oxidation states of all atoms in a neutral molecule must be zero.
Standard oxidation states:
- Hydrogen (H) = \(+1\)
- Oxygen (O) = \(-2\)
Step 3: Detailed Explanation:
Let the oxidation state of Phosphorus be \(x\).
The formula is \(H_3PO_4\).
Setting up the equation:
\[ 3 \times (\text{Oxidation state of H}) + 1 \times (\text{Oxidation state of P}) + 4 \times (\text{Oxidation state of O}) = 0 \]
\[ 3(+1) + x + 4(-2) = 0 \]
\[ 3 + x - 8 = 0 \]
\[ x - 5 = 0 \]
\[ x = +5 \]
Step 4: Final Answer:
The oxidation state of Phosphorus in \(H_3PO_4\) is \(+5\).