Complete thermal decomposition of specific compounds

[intemellectual]

[Mentor Note: Thread moved from the schoolwork forums to the technical Chemistry forum]

Homework Statement: Thermal decomposition temperature of sodium oxide and iron oxide
Relevant Equations: Energy required for the separation of sodium oxide (using heat alone) degrees in Celsius … is it possible. What fields of chemistry or equations deal with the separation of compounds using heat energy alone?

Hi there I didn’t know where to put this so I put it in this section seems pretty straightforward and undergrad in its nature. The question is below if you don’t want to read the background info

BACKGROUND INFO : I’ve been spending these past few years researching the energy crisis that humanity seems set to encounter pretty soon and without writing too much, I’m very interested in the thermochemical decomposition of sodium oxide and to a lesser extent iron oxide (because I know it’s much harder, iron has a much higher melting point). Fossil fuels basically fit the criteria for being the best energy source ever. Cheap and abundant (currently), high energy density, high thermal radiation, highly portable. It just sucks that it pollutes and that it will run out soon

The websites that have influenced me the greatest (regarding the energy crisis) are
dothemath.ucsd.edu
Energyskeptic.com
Resourceinsights.com
Bountiful energy.com

And others. I am not benefiting by marketing them.

QUESTION : My question is that at what temperature does sodium oxide completely decompose to its elements of sodium and oxygen. Does applying sufficient heat alone (thermolysis) enable the separation of these elements or are absurd temperatures required (I consider anything above 2700 celsius absurd)

Is there any nifty chart that shows the temperatures required to completely separate these compounds using just heat alone? Sorry if the question sounds dumb it might be because I know that in order to get things to separate usually you need them to combine with another element like carbon or hydrogen (as is often done) along with an electric current using electrolysis.

I assume in the case of the decomposition of sodium oxide that the oxygen will simply combine with surrounding nitrogen once the decomposition occurs. Would that happen? Or would it be a different outcome? Im guessing it wouldn’t happen because both oxygen and nitrogen are negative or positive?

Picture a huge amount of sodium oxide or peroxide sitting in a high temperature bowl like stainless steel or titanium or whatever other container that can withstand the high heat. Then a fresnel lens ontop of the sodium oxide beaming it with solar power.

Or you could heat it up the conventional way idk but obviously you can’t heat it up to 2000 degrees using electricity because most of the industrial coils heated up disintegrate past 1800 degrees (if my memory serves me right) and heating up sodium oxide with fossil fuels to reduce it and use it as an energy source is pointless

MORE BACKGROUND INFO : Im trying to find out if there’s some chemistry genius out there that has tried and researched using these metals as fuel and found a way to easily separate them, or if there’s some way to separate them without using standard electrochemistry because the introduction of electrodes, gases and electricity brings about issues related to corrosion and increased costs. I know thunderf00ts been doing some work related to sodium but his work involves using the sodium for work rather than it’s synthesis and distribution

Sorry if all the things talked about here sound half baked I am not a chemist just a curious mind seeing if the worlds headed to complete dung or not. Electricity alone is not going to power your car or home, at least not without destroying biodiversity. It will also introduce immense pollution, the amount of rock you have to mine using gas powered trucks is also off the charts and likely not practical (at least with lithium anyways) also there is very little recycling going on with todays batteries so how in the hell are we going to recycle enough batteries for the billions of cars in the future if we aren’t even recycling the ones being used now. According to various estimates there’s only enough mineable lithium for 1 or 1.5 billion electric cars let alone the batteries you’d need for the city or your home. Either there’s a solution on the horizon or people need to change their expectations about the future

 

[Merlin3189]

I can't say that I have any sympathy at all with your premise, but I'm intrigued as to why you want to do these processes at all.
Iron metal is very useful stuff and is usually extracted from its oxide by using carbon, which you obviously don't want to use. The iron oxide is raised to around 1600 C by burning carbon, when the iron is freed and the oxygen bound to carbon in CO2. If you don't use carbon, you might heat it electrically and use some other element to bind the oxygen. Aluminium springs to mind, as used in the thermit process. Aluminium is normally obtained by electrolysis, and sadly, carbon is used for electrodes, but they are not intentionally oxidised! I expect serious metallurgical chemists will have other possibilities.

Sodium oxide is a puzzle, as sodium is not usually extracted this way. AFAIK, if you want sodium or oxygen there are perfectly good electrolytic methods for obtaining them both, but not directly from sodium oxide. I'm not even sure where you'd get sodium oxide from, other than burning sodium in oxygen!

 

[Borek]

or people need to change their expectations about the future

That's exactly the case.

What you are looking for is a TGA or DTA curve (Thermal gravimetric analysis or Differential thermal analysis).

Just decomposing the substance is not enough, you also need to separate decomposition products - hot and eager to react. That's neither trivial nor easy.

And yes, we are talking about absurdly high temperatures in general. Iron oxide melts around 1600°C. At this point it loses some of the oxygen, but it is hardly decomposing.

 

[DrJohn]

You might want to google this phrase
research on recycling lithium car batteries

The reason there is not a lot of recycling just now is because the number of electric cars as a percentage of all cars is rather low just now - about 2% to 3% roughly. As the percentage increases (and it is increasing rapidly now) recycling will be come economically viable and then become common. Probably in about five or so years in my opinion as more electric car batteries reach their end of life.

If the battery lasts for 10 years, the numbers being scrapped are low just now. But that will change. Currently in the UK there are close to 800,000 electric cars, but most are relatively new. Go back five years, and there were about 60,000 electric cars in UK. Seven years ago it was roughly 30,000. So the number of batteries being scrapped just now from these five to seven year old cars is not enough to currently sustain the investment to start up a recycling business. But as I said, about five years from now it probably will start to become economically viable.

Note that a scrapped electric car battery is not necessarily a dead battery, I read recently that owners get annoyed when their battery drops to about 80% of its original range and that's when they get replaced. And for older cars that range was not very large, was it? But they can be used for home storage of electricity. The house's solar panels charging them during the day, home owner getting electricity from them in the evening.

Edit.
Having checked number of electric cars in the US, I think recycling there will become common sooner. Probably just a few recycling centres initially in the US, but eventually more will exist.

I also suspect the current existing recycling centres are trying to become the ones whose names everyone will remember in a few years time and become the go to place when the number of batteries for recycling per year gets large. Possibly running at a loss in their early years but establishing their name.

 

[TeethWhitener]

OP, you're looking for something called an Ellingham diagram. It gives the Gibbs energy of formation for binary compounds vs. temperature. You can find a collection of them here:
http://showard.sdsmt.edu/MET320/Handouts/EllinghamDiagrams/Ellingham_v22_Macro.pdf

For the case of sodium oxide, the Gibbs energy of formation becomes positive at above ~2250K, meaning it is thermodynamically favorable for sodium oxide to split into the elements above this temperature. Note that sodium, oxygen, and sodium oxide are all gaseous at this temperature.

For the case of iron oxides, the chart doesn't go out far enough, but it looks like the temperature is well north of 2400K, and again, all the compounds and elements are gaseous at these temperatures.