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Ch.4 - Reactions in Aqueous Solution
Chapter 4, Problem 110b

Assign oxidation numbers to each element in the following ions. (b) SO3

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Oxidation Numbers

Oxidation numbers are a way to keep track of electron transfer in chemical reactions. They represent the hypothetical charge an atom would have if all bonds were ionic. The rules for assigning oxidation numbers include that the oxidation number of an element in its elemental form is zero, and for monoatomic ions, it equals the charge of the ion.
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Rules for Assigning Oxidation Numbers

There are specific rules for assigning oxidation numbers, such as oxygen typically having an oxidation number of -2, and hydrogen usually being +1. In compounds, the sum of oxidation numbers must equal the overall charge of the molecule or ion. For polyatomic ions, this rule helps in determining the oxidation states of individual elements.
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Sulfite Ion (SO3)

The sulfite ion (SO3) consists of one sulfur atom and three oxygen atoms. To assign oxidation numbers in SO3, we start by assigning -2 to each oxygen, leading to a total of -6 from the three oxygens. The sulfur must then have an oxidation number of +4 to balance the overall charge of the ion, which is neutral.
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