Problem 47 - Chemistry The Central Science

Question

Write a balanced equation for each of the following reactions: (a) Sulfur dioxide reacts with water. (b) Solid zinc sulfide reacts with hydrochloric acid.(c) Elemental sulfur reacts with sulfite ion to form thiosulfate. (d) Sulfur trioxide is dissolved in sulfuric acid.

Step-by-Step Solution

Answer

(a) \( SO_2 (g) + H_2O (l) \rightarrow H_2SO_3 (aq) \) (b) \( ZnS (s) + 2 HCl (aq) \rightarrow ZnCl_2 (aq) + H_2S (g) \) (c) \( S (s) + SO_3^{2-} (aq) \rightarrow S_2O_3^{2-} (aq) \) (d) \( SO_3 (g) + H_2SO_4 (aq) \rightarrow H_2S_2O_7 (aq) \)

Step 1: (a) Sulfur dioxide reacts with water.

First, we need to write the general equation for this reaction: SO₂ (g) + H₂O (l) → H₂SO₃ (aq) Now, we can see that the number of atoms for each element matches on both sides, as we have 1 sulfur atom, 2 hydrogen atoms, and 3 oxygen atoms on both the reactant and product sides. This means the equation is already balanced: SO₂ (g) + H₂O (l) → H₂SO₃ (aq)

Step 2: (b) Solid zinc sulfide reacts with hydrochloric acid.

First, let's write the general equation for this reaction: ZnS (s) + HCl (aq) → ZnCl₂ (aq) + H₂S (g) Now, we need to balance the equation. To do this, we see that there are 2 Cl atoms on the product side but only 1 on the reactant side, so we need to add a coefficient of 2 in front of the HCl: ZnS (s) + 2 HCl (aq) → ZnCl₂ (aq) + H₂S (g) Now the equation is balanced, with 1 Zn, 1 S, and 2 H and Cl atoms on both sides.

Step 3: (c) Elemental sulfur reacts with sulfite ion to form thiosulfate.

First, let's write the general equation for this reaction: S (s) + SO₃²⁻ (aq) → S₂O₃²⁻ (aq) Now, we need to balance the equation. The equation is already balanced since there are 1 sulfur atom and 3 oxygen atoms on both sides of the equation.

Step 4: (d) Sulfur trioxide is dissolved in sulfuric acid.

First, let's write the general equation for this reaction: SO₃ (g) + H₂SO₄ (aq) → H₂S₂O₇ (aq) Now, we need to balance the equation. The equation is already balanced since there are 2 sulfur atoms, 2 hydrogen atoms, and 7 oxygen atoms on both sides.

Key Concepts

Sulfur Dioxide Reactions

Sulfur dioxide (SO₂) is a common compound in various chemical reactions. Its interaction with water results in the formation of sulfurous acid. In the balanced equation, we have:

• Reactants: SO₂ (g) + H₂O (l)
• Products: H₂SO₃ (aq)

The sulfur dioxide molecule contains sulfur and oxygen, vital elements that undergo a chemical change when in contact with water. These components rearrange to form sulfurous acid, where the sulfur atom links with three oxygen atoms and two hydrogen atoms, creating a new compound.
This reaction is important in environmental contexts, as sulfurous acid can contribute to acid rain, affecting soil and water bodies negatively if released in large amounts. Despite being already balanced, understanding the arrangement of atoms helps in comprehending how molecular transformations occur in nature.

Zinc Sulfide Reactions

Zinc sulfide (ZnS) reacting with hydrochloric acid (HCl) showcases an example of a typical double displacement reaction. Here, zinc chloride and hydrogen sulfide gas are produced:

• Chemical equation: ZnS (s) + 2 HCl (aq) → ZnCl₂ (aq) + H₂S (g)
• Zn is for zinc, S is for sulfur, HCl provides hydrogen atoms and Cl ions.

To balance this equation, we observe that each side must have an equal number of each type of atom. Initially, more chloride ions are present in the products than in the reactants, requiring an adjustment. That is why we place a coefficient of 2 in front of HCl, signifying two hydrochloric molecules interact with one zinc sulfide molecule.
This reaction is important in industrial processes where it may be used for extracting and refining zinc from its ores or fostering understanding of reactions between sulfides and acids in chemical mining operations.

Thiosulfate Formation

The formation of thiosulfate involves a simple reaction between elemental sulfur and the sulfite ion. The balanced reaction equation is:

• S (s) + SO₃²⁻ (aq) → S₂O₃²⁻ (aq)

This process incorporates one solid sulfur atom and one sulfite ion to produce a thiosulfate ion.
Thiosulfate is an essential part of several processes, like photographic fixing and gold extraction, due to its unique properties. The ability of sulfur atoms to bond in diverse ways allows for the formation of a wide variety of sulfur compounds, with thiosulfate being particularly important for its stability and reactivity in aqueous solutions.
Learning the details of this balance helps in predicting product formation in reactions involving sulfur and sulfate ions, fostering a deeper comprehension of how sulfur chemistry influences many chemical and biological applications.

Sulfur Trioxide Reactions

Sulfur trioxide (SO₃) is a crucial compound in the production of sulfuric acid (H₂SO₄) but can also form other related compounds. When dissolved in sulfuric acid, it forms pyrosulfuric acid. The balanced equation is:

• SO₃ (g) + H₂SO₄ (aq) → H₂S₂O₇ (aq)

This transformation underlies important industrial processes, such as the manufacturing of highly concentrated sulfuric acid solutions.
Sulfur trioxide's role lies in adjusting the sulfur content in solutions, which is extremely important for producing necessary chemicals in various sectors, including automotive and agricultural industries. Understanding how sulfur trioxide will react with other substances is key to managing chemical processes responsibly and efficiently in technological applications.
Learning about these reactions at a fundamental level can demystify practical implications in production, waste management, and even research into alternative chemical processes.