Sciencemadness Discussion Board

Does Mg react with carbonates?

Conure - 21-3-2023 at 11:25

When igniting mixtures of Mg and carbonates, the fire is more intense and colorful than Mg alone. Is this because the mixture is reacting or is it the carbonate decomposing from the heat of burning Mg? I paricularly like the pink flames from K2CO3. SrCO3 looks nice too.

Edit:
What would be the products of the reaction, say with K2CO3? MgO+K2O+C?

[Edited on 21-3-2023 by Conure]

[Edited on 21-3-2023 by Conure]

DraconicAcid - 21-3-2023 at 11:49

Magnesium will continue to burn if you slap it between pieces of dry ice, so I imagine that yes, it would.

Rainwater - 21-3-2023 at 12:29

Quote: Originally posted by Conure  

What would be the products of the reaction


If you really want to know, you can list all the possible combinations of anion and cations, then ill work the thermodynamics of each reaction to see which is more likely to form.

Morgan - 21-3-2023 at 12:30

I always liked that Magnesium burns nicely with Magnesium Sulfate too.

Conure - 30-3-2023 at 11:16

Here are some videos if anyone is curious. Notice that the video with Li2CO3 leaves a black pile, could it be carbon?
https://m.youtube.com/watch?v=Wm7C-o0ovak
https://m.youtube.com/watch?v=E6Ebg5xqV9c
Quote: Originally posted by Rainwater  
Quote: Originally posted by Conure  

What would be the products of the reaction


If you really want to know, you can list all the possible combinations of anion and cations, then ill work the thermodynamics of each reaction to see which is more likely to form.

You mean like this?
2 Mg + K2CO3 = 2 MgO + C + K2O
3 Mg + K2CO3 = 3 MgO + C + 2 K
2 Mg + K2CO3 = 2 MgO + CO + 2 K
Mg + K2CO3 = MgO + CO2 + 2 K
Mg + K2CO3 = MgO + CO + K2O

[Edited on 30-3-2023 by Conure]

Admagistr - 30-3-2023 at 12:05

@CONURE:
Here are some videos if anyone is curious. Notice that the video with Li2CO3 leaves a black pile, could it be carbon?
https://m.youtube.com/watch?v=Wm7C-o0ovak
https://m.youtube.com/watch?v=E6Ebg5xqV9c


Great YouTube channel! I believe it is carbon,the chemistry of Li and Mg is similar,although they are metals from different groups,there is a diagonal relationship,a peculiarity of the Periodic law...



[Edited on 30-3-2023 by Admagistr]

Rainwater - 30-3-2023 at 13:04

Quote: Originally posted by Conure  

You mean like this?

Yep. So at stp get
Code:
2 Mg + K2CO3 = 2 MgO + C + K2O| ΔH -408.9442 kJ/mol ΔS -65.2578 J mol/K ΔG -389.4875 kJ/mol 3 Mg + K2CO3 = 3 MgO + C + 2 K| ΔH -643.7500 kJ/mol ΔS -34.8151 J mol/K ΔG -633.3701.kJ/mol 2 Mg + K2CO3 = 2 MgO + CO + 2 K| ΔH -156.3142 kJ/mol ΔS 162.1802 J mol/K ΔG -204.6683 kJ/mol Mg + K2CO3 = MgO + CO2 + 2 K| ΔH 158.6991 kJ/mol ΔS 150.0466 J mol/K ΔG 113.9627 kJ/mol Mg + K2CO3 = MgO + CO + K2O| ΔH 78.4918 kJ/mol ΔS 99.0436 J mol/K ΔG 48.9620 kJ/mol

Out of those you listed, at stp 3 are thermodynamicly possible, one of which is favorable at stp.
I have not done a thermite reaction in a while, and im all out of potassium. Might give that a go

[Edited on 30-3-2023 by Rainwater]

Conure - 31-3-2023 at 02:24
Quote: Originally posted by Admagistr  
@CONURE:
Here are some videos if anyone is curious. Notice that the video with Li2CO3 leaves a black pile, could it be carbon?
https://m.youtube.com/watch?v=Wm7C-o0ovak
https://m.youtube.com/watch?v=E6Ebg5xqV9c


Great YouTube channel! I believe it is carbon,the chemistry of Li and Mg is similar,although they are metals from different groups,there is a diagonal relationship,a peculiarity of the Periodic law...


Nice to see that someone appreciates my videos. I'm going to test carbonates with Ca next time. Although I have no more Li2CO3.
Quote: Originally posted by Rainwater  



Quote: Originally posted by Conure  

You mean like this?

Yep. So at stp get
Code:
2 Mg + K2CO3 = 2 MgO + C + K2O| ΔH -408.9442 kJ/mol ΔS -65.2578 J mol/K ΔG -389.4875 kJ/mol 3 Mg + K2CO3 = 3 MgO + C + 2 K| ΔH -643.7500 kJ/mol ΔS -34.8151 J mol/K ΔG -633.3701.kJ/mol 2 Mg + K2CO3 = 2 MgO + CO + 2 K| ΔH -156.3142 kJ/mol ΔS 162.1802 J mol/K ΔG -204.6683 kJ/mol Mg + K2CO3 = MgO + CO2 + 2 K| ΔH 158.6991 kJ/mol ΔS 150.0466 J mol/K ΔG 113.9627 kJ/mol Mg + K2CO3 = MgO + CO + K2O| ΔH 78.4918 kJ/mol ΔS 99.0436 J mol/K ΔG 48.9620 kJ/mol

Out of those you listed, at stp 3 are thermodynamicly possible, one of which is favorable at stp.
I have not done a thermite reaction in a while, and im all out of potassium. Might give that a go

[Edited on 30-3-2023 by Rainwater]

Enthalpy of formation and such is above my chemistry level. ;) I guess lowest number means most likely formula. Do you do the calculations manually or is there some website where you can just paste a chemical formula?

[Edited on 31-3-2023 by Conure]

[Edited on 31-3-2023 by Conure]

[Edited on 31-3-2023 by Conure]

[Edited on 31-3-2023 by Conure]

Admagistr - 31-3-2023 at 03:15

@Conure:Nice to see that someone appreciates my videos. I'm going to test carbonates with Ca next time. Although I have no more Li2CO3.

I like the fact that your channel is very lively and dynamic, no one who I watches adds 5 videos in one day, that's great!Please show more how the products of the reactions look like, if they can be used, for example the metals formed by the reaction. If you add a product to the reaction,for example,when you are doing reacts with aluminium,you add Al2O3,the reaction time is significantly longer,you can observe it better and the products are more separated when the mixture is hot longer...You can use these exothermic reactions as a heat source to realize endotermic reactions,for example,I am experimenting with melting a mixture of Al2O3 and Cr2O3 and trying to make rubies in many ways...;)Greetings to Sweden:)
Good luck with the next experiments,looking forward to the videos!









[Edited on 31-3-2023 by Admagistr]

unionised - 31-3-2023 at 09:37

Have you ruled our carbides etc?

blogfast25 - 31-3-2023 at 10:38

Quote: Originally posted by Conure  


Enthalpy of formation and such is above my chemistry level. ;) I guess lowest number means most likely formula. Do you do the calculations manually or is there some website where you can just paste a chemical formula?



Rainwater loves parading these Standard Enthalpies of Reaction (SER), without seemingly realising how irrelevant they often are.

In chemistry we have a saying: 'thermodynamics does not equate kinetics'.

A simple example shows this. We all know that coal burns fiercely and with much heat (enthalpy) released. But does a lump of coal spontaneously combust at room temperature, considering its strongly negative SER? Does it f*ck!

We need to light that fire, literally with some heat source like a match, lighter, gas burner or similar.

So it is also with those reactions involving Mg: they need to be lit, Thermite-style, in order to proceed, regardless of their SER.

[Edited on 31-3-2023 by blogfast25]

Texium - 31-3-2023 at 10:49

And these are indeed thermite-style reactions being discussed, so the SERs are quite relevant in this context even if they aren’t the end-all be-all.

Once again with the unnecessary aggression from you…

blogfast25 - 31-3-2023 at 11:50

Quote: Originally posted by Texium  

Once again with the unnecessary aggression from you…


If any disagreement on what is supposed to be a site ABOUT SCIENCE now counts as 'aggression' then so be it.

Rainwater - 31-3-2023 at 12:14

Quote: Originally posted by blogfast25  

Rainwater loves parading these Standard Enthalpies of Reaction (SER), without seemingly realising how irrelevant they often are.

Blogfast is correct in that mixing these 2 reagents together, will not cause this reaction to occure. To elaborate, the reagents need to be mixed very well and activation energy added into the system. This happens best when 1 or more are in a liquid or gas state.
but that would be better phrased as, rainwater forgot again, to mentioning how thermodynamics is one part of a bigger concept and not a direct answer.

Any unknown reaction can be written down, and calculated to see if it will happen under given conditions. If the delta G is negative, its is possible. Does not mean it will work, but possible.
If the delta G is positive, not happening

Most books teach the reactivity series, and most of the time that is enough to predict the outcome in aqueous solution, but what do you look for when their is no aqueous solution?
thermodynamics.

Here is the a excel spread sheet i used
https://www.sciencemadness.org/whisper/viewthread.php?tid=15...
If you have questions about it, please use the link above as to keep topics properly sorted

[Edited on 31-3-2023 by Rainwater]

Texium - 31-3-2023 at 12:48

Quote: Originally posted by blogfast25  
Quote: Originally posted by Texium  

Once again with the unnecessary aggression from you…
If any disagreement on what is supposed to be a site ABOUT SCIENCE now counts as 'aggression' then so be it.
It’s possible to disagree without being rude. It shouldn’t be that hard.

blogfast25 - 31-3-2023 at 14:25

Quote: Originally posted by Texium  
It’s possible to disagree without being rude. It shouldn’t be that hard.


There was no rudeness, except in your eyes. It might also be better to allow the subject of perceived rudeness to respond him/herself.

@rainwater: thanks; read and noted.

j_sum1 - 31-3-2023 at 16:25

Quote: Originally posted by blogfast25  
Quote: Originally posted by Texium  
It’s possible to disagree without being rude. It shouldn’t be that hard.


There was no rudeness, except in your eyes. It might also be better to allow the subject of perceived rudeness to respond him/herself.

@rainwater: thanks; read and noted.
Well, blogfast, your expertise on these reactions is appreciated but the swearing was un-needed in this context. i believe that was what Tex was referring to.

arkoma - 31-3-2023 at 17:20

Everybody,

Let's all take a breath and go our respective corners. Please.

Traffic here has gotten sparse enough without needless incivility.

Thank You.

clearly_not_atara - 31-3-2023 at 18:48

Rainwater's use of "standard temperature and pressure" to analyze the behavior of a burning mixture is obviously wrong.

But sometimes reviewing the obvious can be an inspiration to creative thinking. Without glancing at the enthalpies I would have forgotten that it is favorable for some reason for magnesium to reduce potassium. This would likely explain the colorful behavior noted by OP, since potassium is much more volatile than Mg and may mix more effectively with air, as well as producing its own flame colors. Potassium flame e.g.:

Conure - 3-4-2023 at 12:42

Quote: Originally posted by Admagistr  
@Conure:Nice to see that someone appreciates my videos. I'm going to test carbonates with Ca next time. Although I have no more Li2CO3.

I like the fact that your channel is very lively and dynamic, no one who I watches adds 5 videos in one day, that's great!Please show more how the products of the reactions look like, if they can be used, for example the metals formed by the reaction. If you add a product to the reaction,for example,when you are doing reacts with aluminium,you add Al2O3,the reaction time is significantly longer,you can observe it better and the products are more separated when the mixture is hot longer...You can use these exothermic reactions as a heat source to realize endotermic reactions,for example,I am experimenting with melting a mixture of Al2O3 and Cr2O3 and trying to make rubies in many ways...;)Greetings to Sweden:)
Good luck with the next experiments,looking forward to the videos!









[Edited on 31-3-2023 by Admagistr]

I'm too lazy to play around with the products. I did mix some KClO4 with the black and white remains and tried to light it to no avail. I was hoping the black stuff wluld be graphite and ignite. I might try adding Al2O3 to slow down reactions.