Yes, dehydration reactions are endothermic.
The provided reference states directly: "Dehydration, being endothermic, represents the energy storage step while the exothermic hydration of MOy releases the thermal energy on demand." This means that dehydration reactions require an input of energy to occur.
Understanding Endothermic Reactions
Endothermic reactions are chemical reactions that absorb heat from their surroundings. This absorption of heat results in a decrease in the temperature of the surroundings.
Dehydration Reaction Example
Consider a general dehydration reaction:
Hydrate + Heat --> Anhydrous Compound + Water- Reactants: A hydrate (a substance containing water) requires heat input.
- Products: An anhydrous compound (the substance without water) and water are formed.
Why Dehydration is Endothermic
The process of removing water molecules from a compound requires breaking chemical bonds or intermolecular forces. Breaking bonds always requires energy. This energy is absorbed from the surroundings in the form of heat, making the reaction endothermic.
Dehydration in Energy Storage
The reference also highlights the potential use of dehydration reactions in energy storage. Because dehydration is endothermic, it stores energy in the form of chemical potential energy within the anhydrous compound and the separated water. When the reverse reaction (hydration) occurs, this stored energy is released as heat (exothermic reaction). This cycle is described in the reference: "The water vapor produced during the dehydration reaction can be condensed in a reservoir and then reused in vapor phase for the hydration reaction closing the cycle."
