The acid-catalyzed dehydration we learned in this chapter is reversible, as shown below.

(c) Which side of the reaction would be favored by running the reaction at low temperatures?

Verified step by step guidance

1. Step 1: Begin by recalling the principle of Le Chatelier's Principle, which states that a system at equilibrium will adjust to counteract changes in conditions such as temperature, pressure, or concentration.
2. Step 2: Understand that the acid-catalyzed dehydration reaction involves the conversion of an alcohol to an alkene and water. This reaction is reversible, meaning the equilibrium can shift toward either the reactants or products depending on the conditions.
3. Step 3: Consider the thermodynamics of the reaction. Dehydration reactions (formation of alkene and water) are typically endothermic, meaning they absorb heat. Conversely, the reverse reaction (hydration of the alkene) is exothermic, releasing heat.
4. Step 4: Apply the temperature condition given in the problem. At low temperatures, the exothermic direction (hydration of the alkene) is favored because the system will shift to release heat and counteract the lower temperature.
5. Step 5: Conclude that running the reaction at low temperatures would favor the side of the reaction where the alkene is hydrated back into the alcohol, shifting the equilibrium toward the reactants (alcohol and water).

Key Concepts

Le Chatelier's Principle

Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, the system will adjust to counteract the change and restore a new equilibrium. In the context of acid-catalyzed dehydration, this principle helps predict how changes in temperature will affect the position of equilibrium between reactants and products.

Reaction Equilibrium

Reaction equilibrium refers to the state in which the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products. Understanding this concept is crucial for analyzing how temperature influences the favorability of either the reactants or products in a reversible reaction.

Effect of Temperature on Reaction Direction

The effect of temperature on reaction direction is based on whether the reaction is exothermic or endothermic. Lowering the temperature favors the exothermic direction of a reversible reaction, which can help determine which side of the equilibrium will be favored under specific conditions, such as low temperatures in the dehydration reaction.