Industrial Chemistry: Haber & Contact Processes

22 question-and-answer flashcards covering the importance of industrial processes, detailed conditions, equilibria, redox aspects, catalysts, economic/environmental considerations, and key facts about the Haber and Contact Processes.

Why are industrial chemical processes important?

They allow large-scale production of useful chemicals while ensuring economic viability, minimizing environmental impact, and maximizing yield and reaction rate.

Which two major industrial processes rely on equilibrium and redox chemistry?

The Haber Process (ammonia) and the Contact Process (sulfuric acid).

Write the balanced equilibrium equation for the Haber Process.

N₂(g) + 3 H₂(g) ⇌ 2 NH₃(g) ΔH = –92 kJ mol⁻¹.

What are the two raw materials for the Haber Process?

Nitrogen from air and hydrogen from natural gas (methane) or electrolysis of water.

State the optimal temperature, pressure, and catalyst used in the Haber Process.

≈450 °C, ≈200 atm, iron (Fe) catalyst.

Why is ~450 °C used in the Haber Process rather than a higher temperature?

Higher temperatures speed up the rate but lower the equilibrium yield of ammonia because the reaction is exothermic; 450 °C is a compromise.

How does pressure affect the Haber Process equilibrium?

Higher pressure shifts equilibrium toward ammonia (fewer gas moles) and increases yield, but it is costly and poses safety risks.

Does the Haber Process involve redox chemistry? Explain.

Yes; nitrogen is reduced (gains hydrogen, oxidation number decreases) and hydrogen is oxidized (loses electrons in bond formation).

Give the main equilibrium reaction in the Contact Process.

2 SO₂(g) + O₂(g) ⇌ 2 SO₃(g) ΔH = –196 kJ mol⁻¹.

What reaction converts SO₃ to sulfuric acid in the Contact Process?

SO₃ + H₂O → H₂SO₄.

List the raw materials needed for the Contact Process.

Sulfur dioxide (from burning sulfur or roasting sulfide ores), oxygen (air), and water.

State the typical temperature, pressure, and catalyst for the Contact Process.

≈450 °C, 1–2 atm, vanadium(V) oxide (V₂O₅).

Why is only low pressure (1–2 atm) used in the Contact Process?

The equilibrium already strongly favors SO₃, so higher pressure offers little yield advantage and saves cost.

How does vanadium(V) oxide (V₂O₅) function in the Contact Process?

It acts as a redox catalyst, being alternately reduced and re-oxidised to speed up the SO₂ → SO₃ conversion without altering equilibrium.

Explain the redox changes for sulfur and oxygen in the Contact Process.

Sulfur in SO₂ is oxidized from +4 to +6 in SO₃, while O₂ supplies the oxygen and is effectively reduced within the catalytic cycle.

Name four major uses of sulfuric acid produced by the Contact Process.

Manufacture of fertilisers (e.g., ammonium sulfate), production of detergents and paints, petroleum refining, and electrolyte in lead-acid batteries.

How do industrial chemists apply Le Châtelier’s principle to optimize processes?

They choose moderate temperatures, high pressures when products have fewer gas molecules, use catalysts to speed equilibrium attainment, and recycle unreacted reactants.

List three main economic factors considered when designing an industrial process.

Energy costs versus yield, cost of high-pressure or specialized equipment, and overall conversion efficiency.

Identify two key environmental concerns associated with large-scale chemical production.

Release of toxic gases such as SO₂ causing acid rain, and issues of catalyst disposal and material sustainability.

What compromise conditions are common to both the Haber and Contact processes?

Moderate temperature (~450 °C) to balance rate and yield, and the use of a solid catalyst to accelerate reaction without shifting equilibrium.

How do catalysts influence industrial equilibria?

They increase the reaction rate by providing an alternative pathway with lower activation energy but do not change the equilibrium position.

Summarize the main products and catalysts of the Haber and Contact processes.

Haber: produces NH₃ using an iron catalyst at 200 atm and 450 °C; Contact: produces H₂SO₄ using V₂O₅ at 1–2 atm and 450 °C.