Question

Write a balanced chemical equation to correspond to each of the following verbal descriptions: (a) \(\mathrm{NiO}(s)\) can be solubilized by leaching with aqueous sulfuric acid. (b) After concentration, an ore containing the mineral carrollite \(\left(\mathrm{CuCo}_{2} \mathrm{~S}_{4}\right)\) is leached with aqueous sulfuric acid to produce a solution containing copper ions and cobalt ions. (c) Titanium dioxide is treated with chlorine in the presence of carbon as a reducing agent to form \(\mathrm{TiCl}_{4}\). (d) Under oxygen pressure \(\mathrm{ZnS}(\mathrm{s})\) reacts at \(150^{\circ} \mathrm{C}\) with aqueous sulfuric acid to form soluble zinc sulfate, with deposition of elemental sulfur.

Short answer

(a) NiO(s) + H₂SO₄(aq) ⟶ NiSO₄(aq) + H₂O(l) (b) CuCo₂S₄(s) + 4H₂SO₄(aq) ⟶ Cu²⁺(aq) + 2Co²⁺(aq) + 4H₂S(aq) + 4HSO₄¯(aq) (c) TiO₂(s) + 2Cl₂(g) + C(s) ⟶ TiCl₄(l) + CO₂(g) (d) ZnS(s) + O₂(g) + H₂SO₄(aq) ⟶ ZnSO₄(aq) + S(s) + H₂O(l)

Step-by-step solution

Identify reactants and products

In this reaction, solid nickel oxide (NiO) reacts with aqueous sulfuric acid (H₂SO₄) to form soluble nickel sulfate and water.

Write the unbalanced equation

The unbalanced equation can be written as: NiO(s) + H₂SO₄(aq) ⟶ NiSO₄(aq) + H₂O(l)

Balance the equation

Since the equation is already balanced, it remains unchanged: NiO(s) + H₂SO₄(aq) ⟶ NiSO₄(aq) + H₂O(l) #b) Balancing the reaction of carrollite with sulfuric acid#

Identify reactants and products

In this reaction, carrollite (CuCo₂S₄) reacts with aqueous sulfuric acid (H₂SO₄) to produce a solution containing copper ions (Cu²⁺) and cobalt ions (Co²⁺).

Write the unbalanced equation

The unbalanced equation can be written as: CuCo₂S₄(s) + H₂SO₄(aq) ⟶ Cu²⁺(aq) + 2Co²⁺(aq) + 4HS¯(aq)

Balance the equation

After balancing, we get: CuCo₂S₄(s) + 4H₂SO₄(aq) ⟶ Cu²⁺(aq) + 2Co²⁺(aq) + 4H₂S(aq) + 4HSO₄¯(aq) #c) Balancing the reaction of titanium dioxide with chlorine and carbon#

Identify reactants and products

In this reaction, titanium dioxide (TiO₂) reacts with chlorine gas (Cl₂) and carbon (C) to form titanium tetrachloride (TiCl₄).

Write the unbalanced equation

The unbalanced equation can be written as: TiO₂(s) + Cl₂(g) + C(s) ⟶ TiCl₄(l)

Balance the equation

After balancing, we get: TiO₂(s) + 2Cl₂(g) + C(s) ⟶ TiCl₄(l) + CO₂(g) #d) Balancing the reaction of ZnS with oxygen and sulfuric acid#

Identify reactants and products

Under oxygen pressure, zinc sulfide (ZnS) reacts with aqueous sulfuric acid (H₂SO₄) to form soluble zinc sulfate (ZnSO₄) and elemental sulfur (S).

Write the unbalanced equation

The unbalanced equation can be written as: ZnS(s) + O₂(g) + H₂SO₄(aq) ⟶ ZnSO₄(aq) + S(s)

Balance the equation

After balancing, we get: ZnS(s) + O₂(g) + H₂SO₄(aq) ⟶ ZnSO₄(aq) + S(s) + H₂O(l)

Key concepts

Leaching Process

The leaching process is a significant method in industrial chemistry, especially in the extraction of metals. It involves dissolving a solid into a liquid, forming a solution that allows for separation of valuable components.

• In metallurgy, leaching is often used to extract metals from their ores using acidic or basic aqueous solutions.
• One prevalent use of leaching is in the processing of ores to extract compounds like copper, cobalt, and zinc.

During leaching, carefully selected solvents are employed to ensure the effective dissolution of specific substances while leaving impurities behind. This method improves the metal concentration in ores and is financially and environmentally advantageous.
The chemical reactions outlined in a leaching process depend on the reactants, such as nickel oxide or sulfuric acid, as seen in the equations provided in the exercise.

Aqueous Solutions

Aqueous solutions, where water is the solvent, play a crucial role in many chemical reactions, including those in metallurgy.

• Water's remarkable properties make it an ideal solvent for dissolving a wide range of substances, allowing them to interact and form new products.
• In the context of metallurgy, aqueous solutions are used to dissolve metallic ores for extraction through methods like leaching.

An aqueous solution's behavior is governed by its concentration, temperature, and the nature of solutes present. Often, water's polarity and ability to hydrogen bond enable it to effectively separate ions in compounds such as sulfates or chlorides.
Specific examples include the dissolution of sulfuric acid in water to create acidic conditions necessary for the leaching of metals like nickel and copper.

Chemical Reactions in Metallurgy

Chemical reactions in metallurgy are central to the transformation of ores into usable metals. These reactions typically involve reduction processes, where metal ions are converted into pure metal.

• For instance, titanium dioxide reacts with chlorine and carbon in a reduction process to produce titanium tetrachloride.
• These reactions often require specific reactants and conditions, like high temperatures or pressures, to proceed efficiently.

Metallurgical reactions might be influenced by the type of reactants, such as oxidation states, as well as the different phases of matter involved. These conditions not only affect the rate and efficacy of the reactions but also help in minimizing energy consumption and maximizing metal yield.
Understanding these reactions provides insights into refining and processing metals from their naturally occurring states.

Oxidation-Reduction Reactions

Oxidation-reduction reactions, or redox reactions, are chemical processes that involve the transfer of electrons between two species. This transfer alters the oxidation states of the reacting molecules, which is critical in many metallurgical processes.

• In metallurgy, redox reactions are pivotal for extracting metals from their ores, such as zinc sulfide's conversion to zinc sulfate when exposed to oxygen and sulfuric acid.
• These reactions often involve oxidants and reductants, which either donate or accept electrons to drive chemical changes.

A clear understanding of redox principles helps in balancing chemical equations, ensuring the conservation of mass and charge. This knowledge aids in predicting reaction outcomes and improving processes for maximizing metal recovery from ores.
The balanced equations provided earlier reflect these fundamental redox reactions, exemplifying their importance in industrial chemistry.