Question

Give the formula of (a) an anion in which \(S\) has an oxidation number of \(-2\). (b) two anions in which \(\mathrm{S}\) has an oxidation number of \(+4\). (c) two different acids of sulfur.

Short answer

(a) An anion with sulfur having an oxidation number of -2 Anion: \(\mathrm{S}^{2-}\) (b) Two anions with sulfur having an oxidation number of +4 Anions: 1. \(\mathrm{SO_4^{2-}}\) (sulfate ion) 2. \(\mathrm{S_2O_3^{2-}}\) (thiosulfate ion) (c) Two different acids of sulfur Acids: 1. \(\mathrm{H_2SO_4}\) (sulfuric acid) 2. \(\mathrm{H_2SO_3}\) (sulfurous acid)

Step-by-step solution

(a) An anion with sulfur having an oxidation number of -2

To determine an anion where sulfur has an oxidation number of -2, we need to consider that anions are negatively charged, and sulfur needs to gain 2 electrons to reach the oxidation state of -2. When sulfur gains two electrons, it forms a sulfide anion, represented as \(\mathrm{S}^{2-}\). So, the answer is: $$\mathrm{S}^{2-}$$

(b) Two anions with sulfur having an oxidation number of +4

Now, we need to find two anions where sulfur has an oxidation number of +4. To determine these, let's look at oxyanions of sulfur, which are anions containing sulfur and oxygen atoms. We'll find two anions where the total charge of the oxygen atoms equals the charge of sulfur minus 4: 1. The first anion we'll consider is the sulfate ion. The sulfate ion has the formula \(\mathrm{SO_4^{2-}}\). In this ion, there are four oxygen atoms, each with an oxidation state of -2. The total charge of the four oxygen atoms is \(-8\). Therefore, the charge of the sulfur atom in the sulfate ion is: $$\mathrm{-4 = Charge\ of\ S + Charge\ of\ O}$$ $$\mathrm{+4}$$ So, the first anion is the sulfate ion, \(\mathrm{SO_4^{2-}}\). 2. The second anion we'll consider is the thiosulfate ion. The thiosulfate ion has the formula \(\mathrm{S_2O_3^{2-}}\). In this ion, there are three oxygen atoms with an oxidation state of -2 and another sulfur atom with an oxidation state of -2. Therefore, the total charge of all atoms in the ion, except for the one sulfur atom we're considering, is -8. So, the charge of the sulfur atom in question is: $$\mathrm{-4 = Charge\ of\ S + Charge\ of\ O + Charge\ of\ S}$$ $$\mathrm{+4}$$ Thus, the second anion is the thiosulfate ion, \(\mathrm{S_2O_3^{2-}}\). The two anions where sulfur has an oxidation number of +4 are: $$\mathrm{SO_4^{2-}}$$ $$\mathrm{S_2O_3^{2-}}$$

(c) Two different acids of sulfur

Finally, we need to find two different acids of sulfur. Acids containing sulfur usually have the general formula \(\mathrm{H_2SO_n}\), where \(\mathrm{n}\) is an integer. 1. The first acid we'll consider is sulfuric acid. Sulfuric acid has the formula \(\mathrm{H_2SO_4}\). It is formed when the sulfate ion (\(\mathrm{SO_4^{2-}}\)) gains two hydrogen atoms from a proton donor: $$\mathrm{H_2SO_4}$$ 2. The second acid we'll consider is sulfurous acid. Sulfurous acid has the formula \(\mathrm{H_2SO_3}\). It is formed when the bisulfite ion (\(\mathrm{HSO_3^{-}}\)) gains a hydrogen atom from a proton donor: $$\mathrm{H_2SO_3}$$ The two acids of sulfur are: $$\mathrm{H_2SO_4} \ (sulfuric\ acid)$$ $$\mathrm{H_2SO_3} \ (sulfurous\ acid)$$

Key concepts

Oxidation Number

In chemistry, the oxidation number represents the number of electrons an atom loses, gains, or appears to use for bonding when forming compounds. It's a helpful tool for understanding the charge distribution within a molecule or ion. For example, sulfur can have multiple oxidation states depending on the compound it forms. In sulfide ions, sulfur has an oxidation number of

• -2, which indicates that sulfur has gained two electrons.

This state is conveyed by the formula \( \mathrm{S^{2-}} \), showcasing that sulfur is accepting the electrons to complete its outer shell.On the other hand:

• In sulfate (\( \mathrm{SO_4^{2-}} \)), sulfur has an oxidation number of +6 since the combined oxidation states involving oxygen add up to balance out the overall charge.
• In thiosulfate (\( \mathrm{S_2O_3^{2-}} \)), sulfur presents a more complex scenario as its oxidation number can vary, but in this context, we're interested in one sulfur holding an oxidation number of +4.

Understanding oxidation numbers is crucial, as they determine how sulfur will interact with other elements when it forms compounds.

Sulfate and Thiosulfate Anions

Sulfate and thiosulfate ions are both oxyanions of sulfur, meaning they are ions that include oxygen and sulfur atoms. Let's break down each of these: In the sulfate ion, \( \mathrm{SO_4^{2-}} \),

• it consists of one sulfur atom bonded to four oxygen atoms.
• Each oxygen atom typically carries a -2 charge.

This setup results in sulfur having a formal oxidation state of +6, but the molecule itself holds a net charge of -2, largely due to the presence of the four oxygen atoms.Meanwhile, the thiosulfate ion, \( \mathrm{S_2O_3^{2-}} \), is characterized by:

• two sulfur atoms and three oxygens.
• One of these sulfur atoms takes on an oxidation number of -2.
• The sulfur we focus on holds an oxidation state of +4.

The distinct structural arrangements in these anions lead to different chemical behaviors. This diversity in chemistry allows sulfur to participate in a wide variety of reactions and have versatile roles in both industrial and biological systems.

Acids of Sulfur

Sulfur forms some of the most well-known oxoacids, the acids possessing oxygen, in the branch of inorganic chemistry. Let's highlight two common examples:The first, sulfuric acid \( \mathrm{H_2SO_4} \), is widely used in a number of industries and is particularly known for:

• Its strong acidic properties.
• Its ability to act as an oxidizing agent.

Derived from sulfate ions, sulfuric acid is critical in manufacturing fertilizers, chemicals, and even in batteries.Sulfurous acid, represented by \( \mathrm{H_2SO_3} \), is another noteworthy acid, albeit weaker than sulfuric acid. It appears when sulfur dioxide is dissolved in water and features:

• A lower oxidation state of sulfur than in sulfuric acid, specifically at +4.
• Its use predominantly found in intermediate synthesis processes.

These acids illustrate sulfur's ability to form compounds with differing properties, impacting various chemical processes from metal refining to pharmaceutical production. Their diverse applications showcase sulfur's importance in science and industry.