Hydration and Dehydration catalyst

[Raindrop78]

For the dehydration of ethanol to ethylene is the catalyst used a zeolite catalyst? and for the hydration is it also a zeolite catalyst just diluted?

[fan96]

Sulfuric acid is used in both cases.

Concentrated sulfuric acid is a dehydrating catalyst, and dilute sulfuric acid is a hydrating catalyst.

[captainhelium]

Yeah as fan96 said, the catalyst used is sulfuric acid for both the hydration of ethylene and the dehydration of ethanol.

Dehydrating ethanol to ethylene requires concentrated sulfuric acid as a catalyst.

Hydrating ethylene to ethanol requires dilute sulfuric acid as a catalyst.

A nice way to remember which catalyst is used is by thinking:
- Hydration implies adding water therefore dilute sulfuric acid is used (dilute sulfuric acid has lots of water compared to concentrated sulfuric acid)
- Dehydration implies 'removing' water therefore concentrated sulfuric acid is used (since there isn't much water in concentrated acid)
It's not really a 'chemistry' way to think about it though but it works lol.

[supR]

Yeah as fan96 said, the catalyst used is sulfuric acid for both the hydration of ethylene and the dehydration of ethanol.

Dehydrating ethanol to ethylene requires concentrated sulfuric acid as a catalyst.

Hydrating ethylene to ethanol requires dilute sulfuric acid as a catalyst.

A nice way to remember which catalyst is used is by thinking:
- Hydration implies adding water therefore dilute sulfuric acid is used (dilute sulfuric acid has lots of water compared to concentrated sulfuric acid)
- Dehydration implies 'removing' water therefore concentrated sulfuric acid is used (since there isn't much water in concentrated acid)

Additionally, a more chemistry way to remember is that more energy is required to break the -OH bond with the CH3CH2- chain in Ethanol, but breaking the relatively unstable double-bond in ethylene is much easier