kclo4
National Hazard
Posts: 916
Registered: 11-12-2004
Location:
Member Is Offline
Mood: No Mood
|
|
Why make methane from acetates?
Well I am not sure were to ask this but
Why does every one make methane from acetates and hydroxides when it would be easier and cheaper to make it from acetone and a water-soluble hydroxide
and water?
|
|
|
BromicAcid
International Hazard
Posts: 3227
Registered: 13-7-2003
Location: Wisconsin
Member Is Offline
Mood: Rock n' Roll
|
|
Probably because acetates are widely avalible and the decarboxylation reaction is fairly reliable and produces good quantites of methane. How does
the reaction with acetone proceed exactly to produce methane, which kinds of yields?
|
|
|
kclo4
National Hazard
Posts: 916
Registered: 11-12-2004
Location:
Member Is Offline
Mood: No Mood
|
|
Well if you add sodium hydroxide to water then add that to acetone it bubbles about the equivalent of vinegar and baking soda so good I guess
|
|
|
Polverone
Now celebrating 21 years of madness
Posts: 3186
Registered: 19-5-2002
Location: The Sunny Pacific Northwest
Member Is Offline
Mood: Waiting for spring
|
|
The water and NaOH grow hot when mixed together. When combined with low-boiling acetone, the mixture boils. Mixing together strong, room-temperature
NaOH solution with acetone does not show any immediate reaction. Neither does mixing acetone with dry NaOH. Both will discolor with the formation of
acetone condensation products after some time (delay depending on temperature and concentration).
PGP Key and corresponding e-mail address
|
|
|
kclo4
National Hazard
Posts: 916
Registered: 11-12-2004
Location:
Member Is Offline
Mood: No Mood
|
|
hmm I will test it better tomorrow why wouldn’t these work
(CH3)2CO + 2NaOH = 2CH4 + Na2CO3
|
|
|
unionised
International Hazard
Posts: 5104
Registered: 1-11-2003
Location: UK
Member Is Offline
Mood: No Mood
|
|
Why would it work?
Just because an equation balances doesn't mean the reaction happens.
In fact, a different reaction takes place producing diacetone alcohol.
|
|
|
kclo4
National Hazard
Posts: 916
Registered: 11-12-2004
Location:
Member Is Offline
Mood: No Mood
|
|
Well stupid me did not think to analyze
|
|
|
denatured
Hazard to Others
Posts: 151
Registered: 7-8-2004
Location: -
Member Is Offline
Mood: HCl 50%?
|
|
I never heard of such a reaction, i think producing Methane in a convenient way can be done by dropping water on Aluminum Carbide.
Al4C3 + 12H2O ---> 3CH4 + 4AL(OH)3
|
|
|
12AX7
Post Harlot
Posts: 4803
Registered: 8-3-2005
Location: oscillating
Member Is Offline
Mood: informative
|
|
You'd think so, but the last time I synthesized some Al4C3 it didn't bubble at all. I've had bad luck with CaC2, too...
However, the yellow metallic crystalline lumps have decomposed entirely to a gray pile sitting on a paper in my room here, so oxygen and/or moisture
certainly do work away at it eventually.
Tim
|
|
|
denatured
Hazard to Others
Posts: 151
Registered: 7-8-2004
Location: -
Member Is Offline
Mood: HCl 50%?
|
|
I don't know what was wrong with me when i said that .... its all because of that ancient textbook.
It says "Another convenient laboratory method of preparing methane is by the action of water on aluminium carbide"
p59.Organic Chemistry - Pavlov Terentyev - MIR
Maybe it is easy way when you have cheap Al carbide but when 50 grams of it sold by 400 USD , things become ugly!
And now i may say acetate-hydroxide route is convenient ... but i am not sure(i have not tried it yet)
12AX7 did you really synthesized Al4C3 ?
as i know it needs extremely high temp. to combine carbon and Al.
|
|
|
12AX7
Post Harlot
Posts: 4803
Registered: 8-3-2005
Location: oscillating
Member Is Offline
Mood: informative
|
|
Ya, just arc-melt some aluminum onto some charcoal. It also sticks to the graphite arc rods, so be careful. 
Tim
|
|
|
Danne123
Harmless
Posts: 7
Registered: 3-7-2005
Member Is Offline
Mood: Learning
|
|
| Quote: | Originally posted by kclo4
Well stupid me did not think to analyze |
How do you analyze if a reaction takes place or not?
We haven´t learnt it yet in the chemistry class yet...
|
|
|
sparkgap
International Hazard
Posts: 1234
Registered: 16-1-2005
Location: not where you think
Member Is Offline
Mood: chaotropic
|
|
Apart from actually performing the reaction  , maybe compute its Gibbs free
energy? (Google for details)
sparky (~_~)
"What's UTFSE? I keep hearing about it, but I can't be arsed to search for the answer..."
|
|
|
Danne123
Harmless
Posts: 7
Registered: 3-7-2005
Member Is Offline
Mood: Learning
|
|
| Quote: | Originally posted by sparkgap
Apart from actually performing the reaction , maybe compute its Gibbs free
energy? (Google for details)
sparky (~_~) |
You are talking about a exothermic reaction.
But there can be two types of reactions exothermic and endothermic. How do you know that it won´t be a endothermic reaction? Since we don´t know if
there will be a reaction or not you can´t calculate "deltaH" or gibbs energy?
What is it called in english?
|
|
|
neutrino
International Hazard
Posts: 1583
Registered: 20-8-2004
Location: USA
Member Is Offline
Mood: oscillating
|
|
The gibbs equation works regardless of whether the reaction is endothermic or exothermic.
In reality, dG doesn't help you much. An equation with a negative dG won't necessarily happen with any speed at STP (like the conversion of
diamond to graphite). A positive dG doesn't mean that the equation doesn't happen, either: it just means that the Keq of the equation is
below 1.
|
|
|
Danne123
Harmless
Posts: 7
Registered: 3-7-2005
Member Is Offline
Mood: Learning
|
|
| Quote: | Originally posted by neutrino
The gibbs equation works regardless of whether the reaction is endothermic or exothermic.
In reality, dG doesn't help you much. An equation with a negative dG won't necessarily happen with any speed at STP (like the conversion of
diamond to graphite). A positive dG doesn't mean that the equation doesn't happen, either: it just means that the Keq of the equation is
below 1. |
How do we know if there will be a reaction or not then? When the gibbs energy won´t help us. 
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
