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Ch.4 - Reactions in Aqueous Solution
Chapter 4, Problem 108b

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

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1
Step 1: Understand the concept of oxidation numbers. Oxidation numbers are used to keep track of electrons in atoms during chemical reactions.
Step 2: Recall the general rules for assigning oxidation numbers. For example, the oxidation number of oxygen is usually -2.
Step 3: Identify the compound in question, which is \( \text{SO}_3 \).
Step 4: Assign the oxidation number of -2 to each oxygen atom in \( \text{SO}_3 \). Since there are three oxygen atoms, the total oxidation number for oxygen is \(-2 \times 3 = -6\).
Step 5: Determine the oxidation number of sulfur. The sum of oxidation numbers in a neutral compound is zero. Therefore, the oxidation number of sulfur must be +6 to balance the -6 from the oxygen atoms.

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Key Concepts

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

Oxidation Number

An oxidation number is a theoretical charge assigned to an atom in a compound, reflecting its degree of oxidation or reduction. It helps in understanding electron transfer in redox reactions. The oxidation number can be positive, negative, or zero, depending on the atom's electron configuration and bonding.
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Rules for Assigning Oxidation Numbers

There are specific rules for assigning oxidation numbers, such as: the oxidation number of an element in its standard state is zero, the oxidation number of a monoatomic ion equals its charge, and in compounds, oxygen typically has an oxidation number of -2, while hydrogen is usually +1. These rules provide a systematic approach to determine oxidation states in various compounds.
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Sulfur Trioxide (SO3)

Sulfur trioxide (SO3) is a chemical compound consisting of one sulfur atom and three oxygen atoms. In this compound, the oxidation state of sulfur can be determined by applying the rules for oxidation numbers, particularly considering that oxygen has an oxidation number of -2. This understanding is crucial for correctly assigning oxidation numbers in SO3.
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