Multiple Choice
Which of the following elements is most likely to have an oxidation number of +2 in its compounds?
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6. Chemical Quantities & Aqueous Reactions
Calculate Oxidation Numbers
Multiple Choice
What is the oxidation state of each individual carbon atom in the oxalate ion, C2O4^{2-}?
A
0
B
+4
C
+2
D
+3
Verified step by step guidance1
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 \(-2\).
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 \(4 \times (-2) = -8\).
Step 3: Let the oxidation state of each carbon atom be \(x\). Since there are 2 carbon atoms, their total contribution is \$2x$.
Step 4: Set up the equation for the sum of oxidation states equal to the overall charge of the ion: \$2x + (-8) = -2$.
Step 5: Solve the equation for \(x\) to find the oxidation state of each carbon atom: \(2x - 8 = -2 \Rightarrow 2x = 6 \Rightarrow x = +3\).
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