Question

In preparation of alkene from alcohol using $ Al_2 O_3$, which is effective factor?

• A. Porosity of $ Al_2 O_3$
• B. Temperature
• C. Concentration
• D. Surface area of $ Al_2 O_3$

Answer 1

The Correct Option is B

The preparation of alkenes from alcohols typically involves a dehydration reaction. In this process, the alcohol is treated with a catalyst such as Al_2O_3, also known as alumina, to facilitate the removal of a water molecule and formation of an alkene. The effectiveness of this reaction can depend on several factors:

1. Temperature: This is the correct answer. The temperature plays a crucial role in the dehydration of alcohols to alkenes. For the reaction to proceed, sufficient thermal energy is needed to overcome the activation energy. Typically, this reaction is carried out at high temperatures (around 300-400°C). At these temperatures, the alcohol loses a water molecule, leading to the formation of the corresponding alkene.
2. Porosity of Al_2O_3: While the porosity can affect the surface area available for the reaction and thus influence the rate, it is not the most critical factor in determining the reaction outcome compared to temperature.
3. Concentration: This generally refers to the concentration of reactants. While high concentrations might lead to faster reactions under some conditions, the thermal energy required for dehydration is more dependent on temperature.
4. Surface area of Al_2O_3: Similar to porosity, a larger surface area could facilitate the reaction by providing more active sites, but again, it is not as crucial as temperature in determining whether the reaction occurs.

Thus, while catalysts like Al_2O_3 facilitate the reaction, the main driving factor for the dehydration of alcohols to form alkenes is temperature. Ensuring the system reaches the required temperature ensures that the reaction proceeds effectively.