basic help needed! (1 Viewer)

[rkk]

Why and how is catalyst used for ethanol dehydration and hydration?

Why is there a reduced availablity of hydroxy groups in cellulose? or is cellulose insoluble only because it is a large molecule??

What is needed to build petrochemicals...dont understand why four or three carbon chains help in cellulose??

thanks =)

 

[XcarvengerX]

Why and how is catalyst used for ethanol dehydration and hydration?

Concentrated sulfuric acid and diluted sulfuric acid are used as a catalyst in dehydration and hydration respectively, so that the intended reaction could occur. The catalyst will iniate the reaction provide you have the molecules needed and heat.

For hydration:
The catalyst will break double bond in ethene, so water can come along and forming ethanol. (Best shown if you did modelling using atom modelling kit)

Similarly for dehydration, only in reverse.

 

[Dreamerish*~]

Why and how is catalyst used for ethanol dehydration and hydration?

Why is there a reduced availablity of hydroxy groups in cellulose? or is cellulose unsoluble only because it is a large molecule??

What is needed to build petrochemicals...dont understand why four or three carbon chains help in cellulose??

thanks =)

Cellulose has a reduced availability of hydroxy groups, because the hydroxy groups which were once attached to the glucose monomers reacted during condensation reaction to produce cellulose and give off water. The water is H₂O, using up the OH from one glucose monomer, and one H from the other glucose monomer.

We need to build petrochemicals from biodegradable resources because currently, they are produced from fossil fuels, which are finite (and almost-finished) resources. Cellulose is a ring of 5 carbons and one oxygen. This carbon-chain structure is somewhat similar to the carbon chain of hydrocarbons, which are produced from the petrochemical industry. If there was an economical way of breaking cellulose into its glucose monomers, we would be able to transform the carbon chain present in cellulose into a useful product which previously could not have been obtained from a biodegradable resource. Cellulose is present in plants so our supply is abundant.

 

[Dragie]

Because the synthesis or decomposition of ethanol involves organic chemistry, the reaction is thus very slow. To initiate a reaction, a catalyst must be used, otherwise the reaction may take a much longer time.