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.

Short answer

a) \(SO2 (g) + H2O (l) \rightarrow H2SO3 (aq)\) b) \(ZnS (s) + 2 HCl (aq) \rightarrow ZnCl2 (aq) + H2S (g)\) c) \(S8 (s) + 8 SO3^{2-} (aq) \rightarrow 8 S2O3^{2-} (aq)\) d) \(SO3 (g) + H2SO4 (l) \rightarrow H2S2O7 (l)\)

Step-by-step solution

a) Sulfur dioxide reacts with water

To balance this equation, we have the reactants sulfur dioxide (SO2) and water (H2O). When they react, they will form sulfurous acid (H2SO3). The balanced equation is: SO2 (g) + H2O (l) -> H2SO3 (aq) This equation represents the reaction where one molecule of sulfur dioxide gas reacts with one molecule of liquid water to produce one molecule of aqueous sulfurous acid.

b) Solid zinc sulfide reacts with hydrochloric acid

In this case, we have solid zinc sulfide (ZnS) reacting with hydrochloric acid (HCl). The products of this reaction are zinc chloride (ZnCl2) and hydrogen sulfide (H2S). The balanced equation is: ZnS (s) + 2 HCl (aq) -> ZnCl2 (aq) + H2S (g) This equation represents the reaction where one mole of solid zinc sulfide reacts with two moles of aqueous hydrochloric acid to form one mole of aqueous zinc chloride and one mole of hydrogen sulfide gas.

c) Elemental sulfur reacts with sulfite ion to form thiosulfate

For this reaction, we have elemental sulfur (S8) reacting with sulfite ion (SO3^2-). Normally an ion would have a counterion, but for the sake of this exercise, let's assume everything balances out so we don't need the counterion. The product is thiosulfate ion (S2O3^2-). The balanced equation is: S8 (s) + 8 SO3^2- (aq) -> 8 S2O3^2- (aq) This equation represents the reaction where one mole of solid elemental sulfur reacts with eight moles of aqueous sulfite ions to produce eight moles of aqueous thiosulfate ions.

d) Sulfur trioxide is dissolved in sulfuric acid

Finally, we have sulfur trioxide (SO3) reacting with sulfuric acid (H2SO4). The product of this reaction is oleum (H2S2O7). The balanced equation is: SO3 (g) + H2SO4 (l) -> H2S2O7 (l) This equation represents the reaction where one mole of sulfur trioxide gas reacts with one mole of liquid sulfuric acid to produce one mole of liquid oleum.

Key concepts

Balancing Equations

Balancing chemical equations is a fundamental skill in chemistry that ensures the conservation of mass in a reaction. By balancing equations, you make sure that the number of atoms for each element is the same on both sides of the equation. This reflects the reality that matter is neither created nor destroyed in chemical reactions.
\(\text{SO}_2 (g) + \text{H}_2\text{O} (l) \rightarrow \text{H}_2\text{SO}_3 (aq)\)
For example, balancing the reaction of sulfur dioxide and water involves ensuring one sulfur atom and three oxygen atoms are present on both sides of the equation. To balance an equation, follow these steps:

• Write down the unbalanced equation.
• Count the number of atoms for each element in both the reactants and products.
• Add coefficients to balance the atoms, starting with the most complex molecule.
• Check to ensure the equation is balanced in terms of both mass and charge.

These steps allow you to solve chemical equations effectively and are essential in understanding many chemical processes. By practicing balancing equations, you'll gain hands-on experience that reinforces the principles of stoichiometry and the law of conservation of mass.

Sulfur Compounds

Sulfur is a fascinating element involved in forming a variety of compounds with diverse chemical properties. These compounds, such as sulfur dioxide ( SO_2 ), zinc sulfide ( ZnS ), and sulfur trioxide ( SO_3 ), play crucial roles in both industrial and biological processes.
Sulfur dioxide and water react to form sulfurous acid ( H_2SO_3 ), which is an important component in the formation of acid rain. This reaction:

• Is a basis to understand sulfur's ability to form acids.
• Demonstrates sulfur's role in atmospheric chemistry.

Similarly, zinc sulfide reacts with hydrochloric acid to form zinc chloride and hydrogen sulfide, a classic example of a double replacement reaction. Understanding these sulfur compounds:

• Highlights sulfur's versatility in bonding.
• Shows sulfur's importance in metal processing.

These reactions underscore the significance of sulfur compounds in broad scientific and practical applications.

Acid-Base Reactions

Acid-base reactions are a type of chemical reaction that involves the transfer of protons. In the context of inorganic chemistry, these reactions are critical for many industrial processes. For example, the reaction between zinc sulfide and hydrochloric acid is represented by the equation:
\(\text{ZnS} (s) + 2 \text{HCl} (aq) \rightarrow \text{ZnCl}_2 (aq) + \text{H}_2\text{S} (g)\)
Here, hydrochloric acid acts as the proton donor, while the sulfide ion from zinc sulfide is the acceptor.

To understand acid-base reactions, focus on these key aspects:

• Identify the acid and base in the reaction.
• Understand that acids donate protons and bases accept protons.
• Recognize the formation of conjugate acids and bases.

These concepts are essential in predicting product formation and understanding the behavior of acids and bases in different environments.

Inorganic Chemistry

Inorganic chemistry focuses on compounds that are not primarily based on carbon-hydrogen bonds. It covers a wide range of substances, including salts, metals, and minerals. The study of reactions such as those involving sulfur compounds and acid-bases ties firmly to inorganic chemistry.
The reaction of elemental sulfur with sulfite ions to form thiosulfate ions illustrates several foundational inorganic concepts:
\(\text{S}_8 (s) + 8 \text{SO}_3^{2-} (aq) \rightarrow 8 \text{S}_2\text{O}_3^{2-} (aq)\)
This reaction showcases:

• The ability of sulfur to form various oxidation states and complex anions.
• The importance of electron transfer processes in constructing multivalent species.

Understanding the trends, reactivity, and properties of inorganic compounds enhances your grasp of broad chemistry principles and their practical uses, from manufacturing to environmental science. Moreover, these principles help in applications such as developing new materials and catalysis.