ChemP22 a question

[ashhadazam]

No .. the pumice part was Al2O3..

I was talking about the black substance X

 

[ashhadazam]

And u r rite catalysts do remain unchanged.. And this was the case here.. catalyst wasnt taking part in the reaction intended.. It underwent another reactoin with oxygen :/

 

[ashhadazam]

We were not DECOMPOSING alcohol... :/ !! If we were we wouldnt get propene would we :S !!! we would get CO2 and water and some carbon and the whole process goes to waste :/ ! SiO2 isnt black AL2O3 isnt black .. only CUO is black

 

[Nevereasy]

Even if it was Al2O3, where did CuO come from?
There is no copper in the whole setup! Saying the black solid was CuO would mean that either X had copper in it (which is not true) or the alcohol had copper in it(which sounds retarded. Therefore CuO being the black solid is impossible.
You wrote CuO right? What was the reason you gave in the second part?

 

[Sandy]

Yeah that's why i think carbon was the sensible answer... i wrote for Al203 for the other reagent that could be used...what did you guys right for that?

 

[Nevereasy]

We never decomposed the alcohol.
I suggested the catalyst X underwent decomposition due to the heat which was provided with it.
The alcohol only underwent dehydration NOT decomposition.

 

[ashhadazam]

i dunt knw.. i ws confused myself.. Copper was used to catalyse the reaction because in the case of tertiary alcohols we do use copper.. !!! The rest just doesnt fit.. !! nothing else is black in color

 

[Sandy]

Except carbon (solid)..some people wrote soot too

 

[ashhadazam]

even iof catalyst X went decomposition, how does it turn black ?? If AL203 decomoposes it would become aluminium which isnt black..
If SIo2 is heated it wont decompose at all .. very heat resistant !

 

[ashhadazam]

the reason copper reacted with oxygen on strong heating which it does :O

 

[Nevereasy]

But the question itself stated the solid was pumice.
Copper can't be the catalyst for dehydration that we know from our core knowledge it had to be either conc H2SO4 which is not possible here or SiO2/Al2O3.
Now that the catalyst is decided we decide where the heck does the black solid come from?
Is it from the alcohol? Nope that's impossible since it wouldn't undergo dehydration then.
Is it coming from the catalyst? Let's see there's heat underneath it, something to do with a BLACK solid? Yes, I see no other possibility other than decomposition.
What exactly is the black solid? I wrote carbon I was unsure of what compound arises from decomposing SiO2. It might be wrong but it's a rational approach to the question.

 

[Nevereasy]

If it was copper CuO would be formed. Yes BUT there wouldn't be any dehydration and the alcohol won't become an alkene since copper DOES NOT catalyse dehydration.
Copper Oxide is not a possibility.

 

[ashhadazam]

For teritary alcohols it does.. THough i never heard of using copper in dehydrating primary or secondary alcohol :O !!!Kher.. God knows We r done with the paper.. the rest remains with the examiners

 

[Sandy]

True. P1 now!

 

[Nevereasy]

Curse them for giving such an obscure question.

 

[ashhadazam]

p1 now.. !!!

 

[ashhadazam]

Curse them for giving such an obscure question.

Yea curse them :mrgreen: :mrgreen:

 

[Cindy for sure]

I wrote carbon and explained that some vaporized alcohol is oxdized to CO2

Then CO2 is reduced by something in X to C

although I'm not quite convinced of myself!

my teacher said that it's Cu2O！！！ :?

 

[Threshhold abuser]

its bblack cuz its racist

wrote cuo though

 

[angel101]

exactly!!whats ur answer to that ashhad????
carbon fits better than CuO