Question

Give a specific example of a chemical equation that illustrates the (a) reaction of a metal sulfide with \(\mathrm{HCl}(\mathrm{aq})\) (b) action of a nonoxidizing acid on a metal sulfite; (c) oxidation of \(\mathrm{SO}_{2}(\mathrm{aq})\) to \(\mathrm{SO}_{4}^{2-}(\mathrm{aq})\) by \(\mathrm{MnO}_{2}(\mathrm{s})\) in acidic solution; (d) disproportionation of \(S_{2} \mathrm{O}_{3}^{2-}\) in acidic solution.

Short answer

The given reactions are: \n(a) \(FeS(s) + 2HCl(aq) \rightarrow FeCl_{2}(aq) + H_{2}S(g)\) \n(b) \(Na_{2}SO_{3}(s) + 2HCl(aq) \rightarrow 2NaCl(aq) + H_{2}O(l) + SO_{2}(g)\) \n(c) \(5SO_{2}(aq) + 2MnO_{2}(s) + 2H_{2}O(l) \rightarrow 2Mn^{2+}(aq) + 5SO_{4}^{2-}(aq) + 4H^{+}(aq)\) \n(d) \(S_{2}O_{3}^{2-}(aq) + 2H^{+}(aq) \rightarrow SO_{2}(aq) + H_{2}O(l) + S(s)\)

Step-by-step solution

Reaction of metal sulfide with HCl

We can use iron sulfide as an example here. When iron sulfide reacts with hydrochloric acid, it produces iron chloride and hydrogen sulfide as a gas. This can be represented as follows: \n\(FeS(s) + 2HCl(aq) \rightarrow FeCl_{2}(aq) + H_{2}S(g)\)

Action of nonoxidizing acid on metal sulfite

In this case, let's consider a nonoxidizing acid like hydrochloric acid coming into action with a metal sulfite - for example, sodium sulfite. Sodium sulfite reacts with hydrochloric acid to form sodium chloride, water, and release sulfur dioxide gas as follows: \n\(Na_{2}SO_{3}(s) + 2HCl(aq) \rightarrow 2NaCl(aq) + H_{2}O(l) + SO_{2}(g)\)

Oxidation of SO_{2} to SO_{4}^{2-} by MnO_{2} in acidic solution

The reaction can be shown as follows: \n\(5SO_{2}(aq) + 2MnO_{2}(s) + 2H_{2}O(l) \rightarrow 2Mn^{2+}(aq) + 5SO_{4}^{2-}(aq) + 4H^{+}(aq)\)

Disproportionation of S_{2}O_{3}^{2-} in acidic solution

Disproportionation is a reaction during which a higher and a lower oxidation state are formed. This can be shown as follows: \n\(S_{2}O_{3}^{2-}(aq) + 2H^{+}(aq) \rightarrow SO_{2}(aq) + H_{2}O(l) + S(s)\)

Key concepts

Metal Sulfide Reaction with HCl

When a metal sulfide reacts with hydrochloric acid (HCl), a fascinating transformation takes place. For instance, consider the reaction with iron sulfide (FeS). When FeS is added to HCl, iron chloride (FeCl₂) and hydrogen sulfide (H₂S) gas are produced:
\[ FeS(s) + 2HCl(aq) \rightarrow FeCl_{2}(aq) + H_{2}S(g) \]
This reaction illustrates typical characteristics found when metal sulfides meet HCl. The release of H₂S gas is notable for its unpleasant smell, akin to rotten eggs. Such reactions are prevalent in many chemical processes and are essential for understanding basic reaction mechanics.

Nonoxidizing Acid and Metal Sulfite

A nonoxidizing acid like hydrochloric acid can react uniquely with metal sulfites. Take sodium sulfite (Na₂SO₃) as an example. When it reacts with HCl, we get sodium chloride (NaCl), water (H₂O), and sulfur dioxide (SO₂) gas:
\[ Na_{2}SO_{3}(s) + 2HCl(aq) \rightarrow 2NaCl(aq) + H_{2}O(l) + SO_{2}(g) \]
This reaction is a straightforward way to produce SO₂, a gas often used in industries such as paper manufacturing. This type of reaction emphasizes the versatility and utility of nonoxidizing acids in producing secondary products efficiently.

Oxidation of SO2

The oxidation of sulfur dioxide (SO₂) to sulfate ions (SO₄²⁻) involves an intriguing interaction. When SO₂ meets manganese dioxide (MnO₂) in an acidic environment, it transforms as follows:
\[ 5SO_{2}(aq) + 2MnO_{2}(s) + 2H_{2}O(l) \rightarrow 2Mn^{2+}(aq) + 5SO_{4}^{2-}(aq) + 4H^{+}(aq) \]
This process is vital in understanding how sulfur transformations occur in nature and technology. The role of MnO₂ as an oxidizing agent showcases how different substances can facilitate complex chemical conversions, such as turning a harmful gas into a useful ion.

Disproportionation Reaction

Disproportionation is a unique type of reaction where a single substance undergoes both oxidation and reduction. Consider thiosulfate ions (S₂O₃²⁻) in an acidic solution. They transform in the following way:
\[ S_{2}O_{3}^{2-}(aq) + 2H^{+}(aq) \rightarrow SO_{2}(aq) + H_{2}O(l) + S(s) \]
This reaction demonstrates how a compound can split into multiple oxidation states, producing sulfur dioxide, water, and elemental sulfur. Disproportionation reactions are essential in many natural and industrial chemical processes, highlighting the diverse behavior of chemical species.