TiniestChemist
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Which element is more energetic: Aluminium or Potassium?
What posseses more energy if oxidized or needs more energy to reduce or gives more energy in batteries or as heat if reacted with anything (which is
all the same)? In any way, by size, by weight, per mole? Which is always overally more energetic?
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Amos
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Not entirely sure what you mean with regards to energetic, but maybe this can help some: http://en.wikipedia.org/wiki/Reactivity_series
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blogfast25
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Quote: Originally posted by TiniestChemist  | | What posseses more energy if oxidized or needs more energy to reduce or gives more energy in batteries or as heat if reacted with anything (which is
all the same)? In any way, by size, by weight, per mole? Which is always overally more energetic? |
The oxidation of Al to alumina is accompanied by a change in Gibbs free energy that is far larger than the equivalent case of K. How much of that
energy can be exploited to provide electrical energy strongly depends on cell design, though.
For simple air oxidation cells, Mg is preferred over Al, because the aluminium hydroxide is so highly insoluble, compared to magnesium hydroxide.
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zed
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Well, Aluminum is a humdinger for energy. Cheap too! Unfortunately, other factors come in to play. Al2O3 is practically insoluble under ordinary
conditions. Aluminum Hydroxide isn't great either. So, Aluminum's surface is usually quickly passivated.
Ah, there. The entire depth of my knowledge on the subject!
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aga
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| Quote: Originally posted by TiniestChemist | | What posseses more energy if oxidized or needs more energy to reduce or gives more energy in batteries or as heat if reacted with anything (which is
all the same)? In any way, by size, by weight, per mole? Which is always overally more energetic? |
In what Context ?
What exactly do you wish to Do, and why are Al and K your chosen elements ?
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Bert
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Thread Moved
17-11-2014 at 15:39 |
j_sum1
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It makes a lot more sense to ask which reaction is more exothermic rather than which element is more energetic.
If you are looking at formation of oxides, then I believe you are correct. Formation of Al2O3 is probably more energetic per gram than potassium.
The same is likely to be true for reaction with acids.
You then need to consider kinetics -- consider the rate of reaction in the conditions that you have chosen. For most reactions K will react to quickly
to control while with Al you will have problems with it passivating.
Beyond that, it really does depend on what you intend to use the energy for. If you want something to take camping and cook your food I doubt that
either material will be much use. If you want a battery then you need to come up with a design, and both elements are problematic. (Li has proved
very successful however.)
Figure out your context first. Reaction second. And then you can make a sensible comparison of not just energy density but also all of the other
factors that are likely to be significant. Energy content is likely to be one of the smaller factors in most cases anyway.
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deltaH
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I read a while ago that researchers working on an aluminium/hydrogen peroxide battery made the discovery that while it was known that very pure
aluminium electrodes passivate and so are pretty useless, aluminium alloys don't and a sludge of aluminium oxide (hydrate?) grows over the aluminium.
I don't have a reference for you, but that should be enough information for you to track it down.
I laughed when reading about this because the researchers stated something along the lines that they would never have made the discovery were it not
for their poverty and so inability to afford very pure aluminium electrodes, settling instead on commercial aluminium products lol.
[Edited on 18-11-2014 by deltaH]
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j_sum1
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All batteries (cells technically) use redox reactions. That is what causes electron flow. You don't make much sense
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j_sum1
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That would be a redox reaction you are talking about.
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Varmint
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First, if you are going to try and re-write electrochemical science all by yourself, you ought to consider using proper terminology.
A "battery" is, in this context, a collection of two or more connected "cells".
Now, take your last post where you decide to school everyone on what is and is not a "battery", and again I assume you mean cell:
"If something does not react when in direct contact, it is not a (cell)"
Then you go on to discount the utility of the aluminum-air (cell) by stating how poor a design it is because "The zinc reacts with water (I assume you
mean air) even when you do not use them".
In the same sweeping statement you discount Li-ion and in fact all (cells).
Well, the rest of us are patiently awaiting your new definition of a battery to be put to practical use. After all, we've been hamstrung, barely able
to accomplish a single thing that would require portable power because so far, what we think we have, simply does not work or is worthlessly
inefficient by your standards.
I think Bert was being kind, this thread belongs in detritus.
[Edited on 18-11-2014 by Varmint]
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diddi
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if there was anything remotely sensible in using aluminium in a cell on a commercial level, don't you think it would already be in the marketplace?
there has been no discussion of the difference in potential between the 2 half cells, which has significantly more to do with efficient power storage
than how much energy there is in an element, whatever that is supposed to mean.
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blogfast25
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| Quote: Originally posted by TiniestChemist |
If all scientists thought like you, nobody would ever discover anything new. And, no I don't think so. Even electricity is just recently discovered.
Few hundred years ago only, semiconductors even more recently.
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True but the path to Al based batteries has already been beaten to death. And someone with such scant knowledge of chemistry as yourself will not make
the breakthrough needed, trust me.
At least familiarise yourself with all prior part, before you go off on a wild goose chase.
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Bert
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The whole thread... Reminds me so much of a few others recently. Border line trolling.
Somehow, with very much the same writing style- Although posted under several very recently registered screen names. A persona that alternately seems
ignorant and enthusiastic, then just a LITTLE too knowledgable about chemistry & technology to have credibly posted the original topic.
Does anyone else see a resemblance between this and other threads/posters?
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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aga
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I can't point a finger at an example at the moment, but Yes, it looks and feels similar to several others i've read.
To be totally clear, this one doesn't conform to what i feel to be a standard format/look-n-feel, so may be of the Ilk rather than of a Clan.
[Edited on 18-11-2014 by aga]
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gdflp
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| Quote: Originally posted by Bert | Charcoal is capable of performing the reduction of Iron ore with only natural draft. IF you are really clever/experienced at building & running
the furnace.
Original poster: I don't like your name.
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That's why your name is changed. BTW does anyone think this could be another reincarnation of PHDchemist?
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phlogiston
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Yes, it was my first thought as well.
Also note his current mood. There was someone that recently registered with the t***chemist nick a few days ago, possibly the same person. Woelen
asked him very politely to change the nick.
[Edited on 18-11-2014 by phlogiston]
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"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
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Etaoin Shrdlu
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He seems to like deleting all his posts but the tops of his threads.
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gdflp
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| Quote: Originally posted by phlogiston | Yes, it was my first thought as well.
Also note his current mood. There was someone that recently registered with the t***chemist nick a few days ago, possibly the same person. Woelen
asked him very politely to change the nick.
[Edited on 18-11-2014 by phlogiston] |
That person is one and the same. Bert changed his name because he didn't like it.
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