What is the oxidation number of carbon in NaHCO3?
A +6
B -4
C +2
D +4
The Correct Answer and Explanation is :
The oxidation number of carbon in NaHCO₃ (sodium bicarbonate) is +4.
Explanation:
To determine the oxidation number of carbon in NaHCO₃, let’s follow a step-by-step approach. The general formula for sodium bicarbonate is NaHCO₃, which consists of sodium (Na), hydrogen (H), carbon (C), and oxygen (O).
Step 1: Assign known oxidation numbers.
- Sodium (Na): Sodium is an alkali metal, and its oxidation number is always +1 in compounds.
- Hydrogen (H): Hydrogen typically has an oxidation number of +1 when it is combined with nonmetals.
- Oxygen (O): Oxygen almost always has an oxidation number of -2 in compounds, with some exceptions (like in peroxides or when bonded to fluorine). Here, we will assume that the oxygen has an oxidation number of -2.
Step 2: Set up the equation based on the sum of oxidation numbers.
In a neutral compound like NaHCO₃, the sum of all the oxidation numbers must equal zero. We can set up the equation for the oxidation numbers of the elements:
[
\text{Oxidation number of Na} + \text{Oxidation number of H} + \text{Oxidation number of C} + 3 \times (\text{Oxidation number of O}) = 0
]
Substitute the known values:
[
(+1) + (+1) + (\text{Oxidation number of C}) + 3 \times (-2) = 0
]
[
1 + 1 + x + (-6) = 0
]
Simplifying:
[
-4 + x = 0
]
Solving for (x), the oxidation number of carbon:
[
x = +4
]
Step 3: Conclusion.
The oxidation number of carbon in NaHCO₃ is +4, which corresponds to option D.
This reasoning is based on standard oxidation state rules and the requirement that the sum of oxidation numbers in a neutral compound equals zero. Thus, the correct answer is D: +4.