What is the oxidation state of each individual carbon atom in the oxalate ion, C2O4^{2-}?

• A. 0
• B. +4
• C. +2
• D. +3

Answer: (C)

Verified step by step guidance

1. Step 1: Write down the formula of the oxalate ion, which is \(\mathrm{C_2O_4^{2-}}\), and note that the overall charge on the ion is \(-2\).
2. Step 2: Recall that oxygen almost always has an oxidation state of \(-2\) in compounds (except in peroxides or when bonded to fluorine). Since there are 4 oxygen atoms, their total contribution to the charge is \$4 \times (-2) = -8$.
3. Step 3: Let the oxidation state of each carbon atom be \(x\). Since there are 2 carbon atoms, their total contribution is \$2x$.
4. Step 4: Set up the equation for the sum of oxidation states equal to the overall charge of the ion: \$2x + (-8) = -2$.
5. Step 5: Solve the equation for \(x\) to find the oxidation state of each carbon atom: \$2x - 8 = -2 \Rightarrow 2x = 6 \Rightarrow x = +3$.