The oxidation number of carbon in glucose (C₆H₁₂O₆) is 0.
Understanding the oxidation state of atoms within a molecule is fundamental in chemistry, especially when analyzing redox reactions. For a complex organic compound like glucose, the average oxidation number of carbon can be determined by applying standard rules.
Understanding Oxidation Numbers
An oxidation number (or oxidation state) is a number assigned to an element in a compound that represents the number of electrons lost or gained by an atom of that element in the compound. It's a hypothetical charge an atom would have if all bonds were 100% ionic.
Here are the general rules used to determine oxidation numbers:
- Rule 1: The sum of the oxidation numbers of all atoms in a neutral compound is zero.
- Rule 2: The oxidation number of oxygen is usually -2 (except in peroxides where it's -1, or superoxides where it's -1/2).
- Rule 3: The oxidation number of hydrogen is usually +1 (except when bonded to a metal, where it's -1).
Calculating the Oxidation Number in Glucose
Let's apply these rules to glucose, which has the chemical formula C₆H₁₂O₆. We want to find the oxidation number of carbon (C).
- Assign known oxidation numbers:
- Hydrogen (H) = +1
- Oxygen (O) = -2
- Set up the equation: Let 'x' be the oxidation number of carbon. Since the compound is neutral, the sum of all oxidation numbers must be zero.
(Number of Carbon atoms × Oxidation number of Carbon) + (Number of Hydrogen atoms × Oxidation number of Hydrogen) + (Number of Oxygen atoms × Oxidation number of Oxygen) = 0
(6 x) + (12 +1) + (6 * -2) = 0 - Solve for x:
6x + 12 - 12 = 0
6x = 0
x = 0 / 6
x = 0
Therefore, the average oxidation number of carbon in glucose is 0.
Breakdown of Oxidation Numbers in Glucose
The following table summarizes the oxidation numbers for each element within the glucose molecule:
| Element | Number of Atoms | Oxidation Number per Atom | Total Oxidation Number |
|---|---|---|---|
| Carbon | 6 | 0 | 0 |
| Hydrogen | 12 | +1 | +12 |
| Oxygen | 6 | -2 | -12 |
| Total | 0 |
Why is the Oxidation Number 0 for Carbon in Glucose?
The zero oxidation state for carbon in glucose is quite common for many carbohydrates. This value arises from the balanced proportion of hydrogen atoms (which tend to donate electron density, giving them a positive oxidation state) and oxygen atoms (which tend to accept electron density, giving them a negative oxidation state) surrounding the carbon atoms. In essence, the electron-donating effect of hydrogen is precisely counteracted by the electron-withdrawing effect of oxygen when averaged across all carbons in the molecule. This balanced state is crucial for glucose's role as a stable energy storage molecule.
For further exploration of oxidation numbers and their applications, you can consult reputable chemistry resources such as Khan Academy.
