4.3 Applications of the Concept of Rate of Reaction
In daily life and various chemical industries, factors affecting the rate of reaction—such as temperature, pressure, and catalysts—are carefully adjusted to control reaction speeds. Lowering the temperature in refrigerators slows down chemical processes that lead to food spoilage, while industries optimize conditions to maximize production rates in processes like the Haber Process and Contact Process.
Learning Objectives
- Explain how adjusting factors such as temperature influences the rate of reaction in daily life activities, such as food storage in a refrigerator.
- Describe the optimal conditions (temperature, pressure, and catalyst) and chemical equations involved in the Haber Process for producing ammonia.
- Describe the stages, chemical equations, and optimal conditions (temperature, pressure, and catalyst) involved in the Contact Process for manufacturing sulphuric acid.
Comparison of Industrial Applications of Rate of Reaction: Haber Process vs. Contact Process
A side-by-side comparison of reactants, products, operating conditions, and flow stages for both industrial processes.
Short Explanation
Controlling Reaction Rates
Controlling reaction rates is vital in both everyday life and chemical manufacturing. Lowering the storage temperature of food in a refrigerator retards spoilage by decreasing the rate of degradation reactions. In industrial chemical production, specific conditions such as high pressure, elevated temperature, and solid catalysts are applied to maximize the rate of formation of target compounds like ammonia in the Haber Process and sulphuric acid in the Contact Process.
Daily Life Application
In daily life and industries, factors affecting the rate of reaction are adjusted to increase or decrease the reaction rate.
Refrigerator. Lowers the temperature of food and drinks kept inside it. The decrease in temperature slows down the rate of reactions that cause food spoilage.
Haber Process (Production of Ammonia)
Purpose: Industrial manufacture of ammonia, \(\text{NH}_3\).
Reactants: A mixture of nitrogen gas, \(\text{N}_2\), and hydrogen gas, \(\text{H}_2\), in a ratio of \(1:3\).
Optimal Conditions:
- Temperature: \(450^\circ\text{C} - 550^\circ\text{C}\)
- Pressure: \(200\text{ atm}\)
- Catalyst: Iron filings, \(\text{Fe}\)
Chemical Equation:
\[\text{N}_2 + 3\text{H}_2 \rightleftharpoons 2\text{NH}_3\]
Process Flow:
- Nitrogen gas and hydrogen gas are fed into a compressor and compressed at a pressure of \(200\text{ atm}\).
- The compressed mixture enters the reactor containing iron filings at \(450^\circ\text{C} - 550^\circ\text{C}\).
- The gases pass into a cooling chamber where ammonia gas cools to form liquid ammonia.
- Unreacted nitrogen and hydrogen gases are recycled back into the reactor.
Contact Process (Production of Sulphuric Acid)
Purpose: Industrial manufacture of sulphuric acid, \(\text{H}_2\text{SO}_4\).
Stages and Chemical Equations:
- Stage 1: Production of sulphur dioxide (\(\text{SO}_2\))
Sulphur is burnt in an excess of air (or dry air): \[\text{S} + \text{O}_2 \rightarrow \text{SO}_2\] - Stage 2: Production of sulphur trioxide (\(\text{SO}_3\))
Sulphur dioxide gas mixed with an excess of air is passed over a catalyst: \[2\text{SO}_2 + \text{O}_2 \rightleftharpoons 2\text{SO}_3\]
Optimal Conditions for Stage 2:
Temperature: \(450^\circ\text{C}\)
Pressure: \(1\text{ atm}\)
Catalyst: Vanadium(V) oxide - Stage 3: Formation of oleum (\(\text{H}_2\text{S}_2\text{O}_7\))
Sulphur trioxide gas is dissolved in concentrated sulphuric acid: \[\text{SO}_3 + \text{H}_2\text{SO}_4 \rightarrow \text{H}_2\text{S}_2\text{O}_7\] - Stage 4: Formation of concentrated sulphuric acid (\(\text{H}_2\text{SO}_4\))
Oleum is diluted with water: \[\text{H}_2\text{S}_2\text{O}_7 + \text{H}_2\text{O} \rightarrow 2\text{H}_2\text{SO}_4\]
Summary of Industrial Conditions
| Industrial Process | Product | Temperature | Pressure | Catalyst |
|---|---|---|---|---|
| Haber Process | Ammonia (\(\text{NH}_3\)) | \(450^\circ\text{C} - 550^\circ\text{C}\) | \(200\text{ atm}\) | Iron filings (\(\text{Fe}\)) |
| Contact Process | Sulphuric acid (\(\text{H}_2\text{SO}_4\)) | \(450^\circ\text{C}\) | \(1\text{ atm}\) | Vanadium(V) oxide |
Try to Answer First
Answer in your mind, then press “Check Answer”.
Why is food kept in a refrigerator able to last longer before spoiling?
What is the catalyst used in the Haber Process, and what are its operating pressure and temperature?
In the Contact Process, which catalyst is used to convert sulphur dioxide into sulphur trioxide?
Common Mistakes
- Confusing the catalysts: using vanadium(V) oxide for the Haber Process instead of iron filings, or using iron filings for the Contact Process instead of vanadium(V) oxide.
- Mixing up the operating pressures: stating \(1\text{ atm}\) for the Haber Process (which requires \(200\text{ atm}\)) or \(200\text{ atm}\) for the Contact Process conversion step (which operates at \(1\text{ atm}\)).
- Incorrectly writing the ratio of nitrogen to hydrogen in the Haber Process as \(3:1\) instead of \(1:3\).
- Forgetting the intermediate product in the Contact Process: sulphur trioxide is first dissolved in concentrated sulphuric acid to form oleum (\(\text{H}_2\text{S}_2\text{O}_7\)) before dilution with water, rather than adding water directly to sulphur trioxide.
Concept Misunderstandings
The Haber Process and Contact Process run at room pressure because high temperature is sufficient.
The Haber Process specifically requires a high pressure of \(200\text{ atm}\) to compress the gaseous reactants and increase the rate of reaction.
Catalysts are consumed as reactants during the industrial manufacture of ammonia and sulphuric acid.
Iron filings and vanadium(V) oxide act as catalysts to increase the rate of reaction without being consumed in the overall reaction.
Summary
- Applications of the rate of reaction include slowing down food spoilage by reducing temperature in refrigerators, and speeding up industrial production using specific combinations of temperature, pressure, and catalysts.
- The Haber Process produces ammonia using nitrogen and hydrogen (\(1:3\) ratio) at \(450^\circ\text{C} - 550^\circ\text{C}\), \(200\text{ atm}\), and iron filings.
- The Contact Process produces sulphuric acid using sulphur, air, and water through multiple stages, utilizing vanadium(V) oxide catalyst at \(450^\circ\text{C}\) and \(1\text{ atm}\).
Short Activity
A. Objective Quiz
1 Which catalyst and pressure are used to increase the rate of reaction in the Haber Process?
2 In the Contact Process, what substance is formed when sulphur trioxide gas is dissolved in concentrated sulphuric acid?
B. Fill in the Blanks
3 In the Haber Process, nitrogen gas and hydrogen gas react in a volume ratio of to produce ammonia gas.
4 In the Contact Process, the catalyst used to convert sulphur dioxide to sulphur trioxide at \(450^\circ\text{C}\) is .
C. Drag and Drop: Match the Process to Its Condition
Drag each application or process to its corresponding condition or feature. On a phone, tap an answer first, then tap a matching box. Tap the Answer Choices area to return a selected item.
C. Match the Process to Its Condition
Write the correct process or application next to each condition.
| Operational Condition or Feature | Application / Process |
|---|---|
| 1. Uses iron filings catalyst at 200 atm and 450°C – 550°C | |
| 2. Uses vanadium(V) oxide catalyst at 1 atm and 450°C | |
| 3. Lowers temperature to slow down reactions causing food spoilage | |
| 4. Added with water to produce concentrated sulphuric acid |
Answer choices: Haber Process • Contact Process • Refrigerator • Oleum dilution
