What is the oxidation number of chlorine in sodium chlorite, NaClO2? a) -1 b) +1 c) +3 d) +5 e) +7
The Correct Answer and Explanation is:
The oxidation number of chlorine in sodium chlorite (NaClO₂) is +3 (option c).
Here’s a breakdown of how we determine this:
- Oxidation numbers of elements:
- Sodium (Na) is in Group 1, and in compounds, it typically has an oxidation number of +1.
- Oxygen (O) in most compounds (except peroxides) has an oxidation number of -2.
- Total charge of the compound:
Sodium chlorite is a neutral compound, meaning the sum of the oxidation numbers of all atoms in the formula must equal zero. - Assign oxidation numbers:
- The oxidation number of sodium (Na) is +1.
- The oxidation number of each oxygen (O) is -2. There are two oxygen atoms, so their total oxidation number contribution is 2×(−2)=−42 \times (-2) = -42×(−2)=−4.
- Set up the equation:
Let the oxidation number of chlorine (Cl) be xxx. The sum of oxidation numbers in NaClO₂ should be zero: (+1)+x+(−4)=0(+1) + x + (-4) = 0(+1)+x+(−4)=0 - Solve for xxx (the oxidation number of chlorine): x=4−1=+3x = 4 – 1 = +3x=4−1=+3
Thus, the oxidation number of chlorine in sodium chlorite (NaClO₂) is +3.
This matches the correct answer: c) +3.
