refluxing (1 Viewer)

[xxxcaixxx]

I forget this bit....
can anyone outline the advangtages of using reflux to prepare the ester.
It'a a question in 2003 HSC..(q21 c)

 

[NothingIsStatic]

It ensures that the product of your esterfication does not escape. It is produced as the gaseous form, and when it hits the reflux tube it will be condensed by the cool water.

Not only that it increases the yeild but it has some safety consideration as the gases are highly flammable...

Hrm. I think that there is more to it though.

 

[wind]

Alkanol and alkanoic acid are both volatile so they vaporise when heated normally before they can react and form the ester.

Refluxing condenses these substances before they evaporate and allows for further reactions to occur.

Something like that at least

Edit: the sulfuric acid catalyst reduces the activation energy needed for the reaction to occur. It also increases yield since the sulfuric removes the water (condensation reaction) and shifts the reaction to the right (products side in equilibrium reaction).

 

[bloodysunday]

well, for one thing it stops anything from evaporating, and you can do it for as long as you like without screwing up the experiment i guess.

 

[Paroissien]

Esterification is endothermic thus increased temp results in increased yield. Refluxing is used to prevent the loss of volatile reactant and products as they are cooled preventing escape. Allows esterification to be performed a higher temp than normally possible

 

[aim54x]

u don't lose ur reactants n products. that is the main reason, otherwise u will end up wit very little to nothing at d end. reflux also allows u to keep reactin for longer

 

[CM_Tutor]

Increased yield as endothermic equilibrium (Le C's P)

Increased yield by preventing loss of volatile reactants

Increased rate of reaction due to heating

Increased safety by preventing loss of flammable reactants

 

[DAAVE]

You should note that it is not sufficient to just say what the refluxing apparatus does. You have to talk about the reason for refluxing, which is outlined above...

 

[aim54x]

reflux cools usin water. reasons are as above.

is cool water fed from the top or bottom???

 

[Paroissien]

Fed from bottom of refluxing apparatus, leaves top

 

[helper]

Best from the bottom in case there is a cut in water supply.