Confused about catalysts in dehydration and hydration of ethanol (1 Viewer)

[lonestar]

Ok, so my dilemma is that several sources are giving me different information about the catalysts in the dehydration of ethanol, and the hydration of ethylene.

With hydration of ethylene to get ethanol, my school teacher said that you needed
*300 degrees
*H2SO4 concentrated
*Zeolite surface catalyst
*Porous Ceramic

I'm so confused - which one, of the last three points is the actual catalyst? Do you even need all those things in that reaction? I've been reading similar threads on this topic, and people have just said that concentrated H2SO4 is the catalyst, but yeah i just want to see what everyone else things of the other two thingos...

With the dehydration of ethanol to get ethylene, my school note say:
*300 degrees (temp)
*conc. H2SO4 - the dehydrating agent
*porous ceramic - the catalyst

People have said that the conc. H2SO4 is the dehydrating agent AND the catalyst.

Could someone clear this up for me? It would be greatly appreciated.

 

[Trebla]

The described concentration of sulfuric acid in the list for hydration is incorrect.
To keep things simple:
- The hydration catalyst is often regarded as DILUTE sulfuric acid. (not concentrated)
- The dehydration catalyst is often regarded as CONCENTRATED sulfuric acid.

 

[onebytwo]

i think of it like this:

hydration, we want to add water, so we can use dilute (cos it has lots of H2O)
dehydration, we want to remove water, so we introduce minimal H2O to the system, thus concentrated

 

[lonestar]

Awesome! Thanx heaps!!! Helped alot

 

[cerebaton]

Heh, I never realised until now, but I always thought of it as:

When you're dehydrated, your piss is concentrated
When you're hydrated, you're piss is dilute

lol, guess it's just one fo those htings you pick up from biology

 

[xiao1985]

i think of it like this:

hydration, we want to add water, so we can use dilute (cos it has lots of H2O)
dehydration, we want to remove water, so we introduce minimal H2O to the system, thus concentrated

second that... that's how i remembered it in HSC...

just so that i don't confuse any HSC'ers, below contains info you don't need to know for HSC chem... read at your leisure/peril:

any acid infact may act as a catalyst during the hydration dehydration of ethanol<-> ethene. H2SO4 just happens to be a good one because conc. H2SO4 ALSO act as a dehydrating agent . which makes dehydrating alot more efficient...

i recall there's a hsc question regarding catalyst of dehydration in a MCQ. two option being HNO3 and H2SO4. the correct answer being, of course, the latter... though i feel rather outrageous at the consistent incompetent scientific knowledge being thought in the syllabus. (ok, just this one point... perhaps there are other examples, but i cannot recall any others)

bitching completed