This question is about alkenes and alcohols - AQA - GCSE Chemistry - Question 10 - 2021 - Paper 2

The conditions for producing ethene typically include high temperatures, usually in the range of 300 to 900 °C, and the presence of steam. A catalyst may also be used to enhance the reaction rate.

To produce ethanol economically from ethene and steam, the following conditions should be considered:

1. Temperature: A higher temperature generally increases the reaction rate due to more frequent collisions; however, too high a temperature may reduce yield, as the reaction is exothermic.

2. Pressure: Increasing pressure can shift the equilibrium to favor the production of ethene, enhancing the yield. However, excessively high pressures can lead to increased costs for maintaining pressure vessels.

3. Catalyst: Using a suitable catalyst can lower the activation energy and increase the rate of the reaction without affecting the equilibrium position.

4. Compromise conditions: The chosen temperature and pressure should represent a compromise between maximizing yield and minimizing costs associated with energy usage and equipment maintenance.

The process by which ethanol is produced from sugar by adding yeast is called fermentation.

To produce butanol from sugar solution using bacteria, the conditions should be warm, typically in the range of 25 °C to 45 °C, and anaerobic, meaning without oxygen.

First, convert the distance travelled into meters: 200 km = 200,000 m.

Next, calculate the total energy needed for this distance:

Total energy = Distance × Energy per meter = 200,000 m × 1.95 kJ/m = 390,000 kJ.

Since the energy content of ethanol is 1300 kJ/mol, we can calculate the number of moles of ethanol required:

Number of moles = Total energy / Energy content per mole = 390,000 kJ / 1300 kJ/mol = 300 moles.

The balanced equation for the complete combustion of butanol (C₄H₁₀O) is:

C₄H₁₀O + 6 O₂ → 4 CO₂ + 5 H₂O.