Ethene --> Ethanol (1 Viewer)

[ND]

Conquering chem at one point says that the catalyst for ethene --> ethanol is phosphoric acid, and at another point says dilute sulfuric acid is used. Which is correct? (or which should i use in the exam)
Thanks.

note: this is from memory, so correct me if i've missed something.

edit: just a side question: why is dilute sulfuric acid used for hydration when it's a dehydrating agent?

 

[jm1234567890]

any will do, it is the (H+) that is the catalyst

for dehydration it has to be concentrated sulphuric acid.

look in my summary it has everything

 

[jims]

i think its dilute H2SO4. mayb H3PO4 is also correct, but ive never read of it.

and in this reaction, its not being used as a dehydrating agent, thats only in ethanol --> ethene which, as jm said, uses concentrated H2SO4.

btw if u look at the equations, the whole H2SO4 molecule takes part in the reaction (and is reformed on completion).

 

[Azn fairies]

lol it's h2so4 for SURE...im 100% sure.. casue it's hyroscpic therefore it sucks h2o and it shifts the equillburm to the right as h2o is taken out therefore increse the rate of reaction

also phosphoric acid is not totally wrong but CC doesn't say that is says h2so4.. if u say phosphoric acidit's half correct becaseu it's also hyroscipic, BUT not very effective casue not a catlacyst it can react with the reaction !!.

hope that's right. preety sure it is.

 

[Jumbo Cactuar]

yeah both are right, but i find it easier to remember and justify H2SO4

 

[Azn fairies]

true.. but if u do put phosphoric acid, all i can say is "GOOD LUCK"...casue not every teacher accpets this answer.

 

[ND]

Originally posted by Azn fairies
lol it's h2so4 for SURE...im 100% sure.. casue it's hyroscpic therefore it sucks h2o and it shifts the equillburm to the right as h2o is taken out therefore increse the rate of reaction

I though hygroscopic meant it absorbs atmospheric water? Anyway, if it were to absorb water, the equilibrium would shift to the left (we're talking about hydration remember).

Ok so either is fine, thanks everyone.

yeah both are right, but i find it easier to remember and justify H2SO4

We don't have to justify the catalyst for hydration of ethene do we? i thought it was only for dehydration?

 

[Azn fairies]

ummm i think it shifts to right casue the equation is

ethene + h20 -> ethanol

so if h2o is sucked out then the euqaillbrum goes rtight... i think that's right?? now im confussed .lol

and no u don't have to justify why u use this catlayst nut i just though i might mention it anyway

 

[iambored]

Originally posted by ND
Conquering chem at one point says that the catalyst for ethene --> ethanol is phosphoric acid, and at another point says dilute sulfuric acid is used. Which is correct? (or which should i use in the exam)
Thanks.

dilute sulfuric, and dehydration is concentrated sulfuric

Originally posted by ND
We don't have to justify the catalyst for hydration of ethene do we? i thought it was only for dehydration?

we have to justify dehydration catalyst? is it in the dot points? is that the thing "explain the need for a catalyst" bcoz i dnt know anything specific about why it's used

 

[Azn fairies]

well the reason is beacsue the rate of reaction is too slow for the reaction to occur, so if u added h2so4, since it';s hydropsic it will take out h20 and drag euilliurum to the right therefore speed up reaction.

 

[Azn fairies]

....

 

[ND]

Originally posted by Azn fairies
ummm i think it shifts to right casue the equation is

ethene + h20 -> ethanol

so if h2o is sucked out then the euqaillbrum goes rtight... i think that's right?? now im confussed .lol

Nope it goes left; if you remove the H2O, it will want to produce more to compensate, shifting the equilibrium to the left.

we have to justify dehydration catalyst? is it in the dot points? is that the thing "explain the need for a catalyst" bcoz i dnt know anything specific about why it's used

Well cos it says "explain", you have to explain why it's needed.

 

[Azn fairies]

Originally posted by ND
Nope it goes left; if you remove the H2O, it will want to produce more to compensate, shifting the equilibrium to the left.


uhm?..well u sadi shifts to the left..then at the end u said equillbrum shifts to the right??.wt?

 

[ND]

Originally posted by Azn fairies
then at the end u said equillbrum shifts to the right??.wt?

I did? Where?

 

[Azn fairies]

lol.. did u just chnage it or am im going blind from all the radation fomr the computer

 

[ND]

Nope i didn't change it. If i did it would say "last edited by ND at .... etc." down the bottom of the post. Maybe you looked at my quote of your post.

 

[Azn fairies]

lol ..yeah maybe...lol so gay.

 

[freaking_out]

Originally posted by ND
Conquering chem at one point says that the catalyst for ethene --> ethanol is phosphoric acid, and at another point says dilute sulfuric acid is used. Which is correct? (or which should i use in the exam)
Thanks.

note: this is from memory, so correct me if i've missed something.

edit: just a side question: why is dilute sulfuric acid used for hydration when it's a dehydrating agent?

yeah, just on ya first question, phoshoric acid is used "industrially" i think coz its prolly a lot cheaper etc...


with the second question, concentrated sulfuric acid is a strong dehydrating agent (rem. esterification) and i "dilute" sulfuric acid is the opposite i guess.

 

[ND]

Re: Re: Ethene --> Ethanol

Originally posted by freaking_out
concentrated sulfuric acid is a strong dehydrating agent (rem. esterification)

Yes.. i do remember.. i got some of that acid on my hand, ouch.

 

[freaking_out]

Re: Re: Re: Ethene --> Ethanol

Originally posted by ND
Yes.. i do remember.. i got some of that acid on my hand, ouch.

yeah, we were pouring it down the sink, as well as diluting it.

all this smoke came out.