Salt fire

[MDJH]

Just then I dipped a piece of wood into a magnesium sulfate solution within a glass. First off is there any chance of the combination of the solution and the wood causing damage to the glass?

 

Anyway, I'm doing this to get the wood to soak in some of the magnesium sulfate solution like how it does with water. I'm guessing that it would soak in some of it, though not much of it. My reason for THAT, in turn, is to have a magnesium sulfate soaked piece of wood to burn on the fire, because I tried burning magnesium sulfate in the fire before by placing some magnesium sulfate onto a piece of wood and putting the wood in the fire; I didn't see the white flame it's supposedly supposed to give off.

 

So therefore, I'd also like to ask; would it be more likely to burn the magnesium sulfate if I were to leave the wood soaking in the solution and put it in the fire wet, (ie. while the wood is still soaked with the solution) or to let it soak for a little while but then dry the wood out (ie. with a blow-dryer or something) so that it has dried magnesium sulfate on it?

 

Also, if this worked, would the white magnesium sulfate fire be too bright to look at with your own eyes (like a flame of magnesium itself would) or would it be mild enough to look at? Or would it be somewhere in between? (ie. mild enough to look at with sunglasses, but not without?)

[Mr Skeptic]

One problem is that wood has lots of sodium in it, which is what makes the flame yellowish, and sodium has a tendency to swamp the other ions in flame tests. Dunno if you can make up for it by putting enough magnesium in it though.

[MDJH]

One problem is that wood has lots of sodium in it, which is what makes the flame yellowish, and sodium has a tendency to swamp the other ions in flame tests. Dunno if you can make up for it by putting enough magnesium in it though.

I didn't know that before. That's interesting... I was actually considering burning wood soaked in table salt to see the "yellow sodium flame" but was thinking that would be pointless as I'd mistake it for wood's yellow flame. Of all the irony that it's BECAUSE of sodium that the wood flame is yellow. XD

 

But yeah, I'm trying to get it to soak in more concentrated epsom salt than I would get at room temperature... if I were to add warm water, to get it to dissolve more epsom salt, would the wood absorb the more concentrated epsom salt before the water cooled down or after? And is it likely that the wood could absorb the concentrated epsom salt, but lose it from the wood after the solution cools down?

[John Cuthber]

Magnesium metal burns with a bright flame. Magnesium sulphate doesn't burn.

[MDJH]

Magnesium metal burns with a bright flame. Magnesium sulphate doesn't burn.

It's odd though, Wikipedia says it does. Well, I left the MgSO4-soaked wood in my hometown, my parents say they might burn it in the fire later and send the pictures to me. I'll find out soon enough. (My mom also threw out the MgSO4 solution on the lawn, not realizing it could kill the grass. XD)

[John Cuthber]

Mag sulphate will decompose at high temperatures to the oxide. Magnesium oxide is used for things like furnace linings; it has a very high melting point and an even higher boiling point. It's hard to see how enough of it would get into a flame to cause a colour.

[Mr Skeptic]

Maybe soaking paper would have been a good idea. Also, if you have a gas stove, that flame is much purer and you can change its color more easily. I've done the flame thing with copper (from an old copper wire) and that turned the flame a lovely green.

[MDJH]

Maybe soaking paper would have been a good idea. Also, if you have a gas stove, that flame is much purer and you can change its color more easily. I've done the flame thing with copper (from an old copper wire) and that turned the flame a lovely green.

I'm guessing I didn't make this clear in my last post, but I left the MgSO4-soaked wood at home, and since starting this thread moved out to the city where I go to university. So I'd need to find out if and where I could safely and legally have a fire out here (not sure yet how to find out) and check on it before doing fire-related experiments with salt and wood out here.

 

But yeah, from now on this thread is about colored fire, or ideally about colored fire via metal cations. So what makes colored fire work anyway, is it that the reaction of the oxygen with the metal cations has a certain amount of energy and therefore gives off a specific wavelength of photons?

 

BTW John Cuthbert, if the MgSO4 decomposes to MgO at high temperatures, would the SO3 be given off as SO3 or in the form of other compounds?

[hermanntrude]

A good method for long-lasting coloured flames is to make a solution of alcohol/water with the relevant metal salt in it. Then set light to the solution. Then you get a coloured flame which lasts long enough to examine it properly.

 

The colours come from electrons which have been excited dropping back down to their ground states (or lower excited states). Because the differences in energy levels are different for each ion, the sizes of the "drops" the electrons make is characteristic of the ions and so is the wavelength of the photons released. For more information, look up atomic emission.

[MDJH]

A good method for long-lasting coloured flames is to make a solution of alcohol/water with the relevant metal salt in it. Then set light to the solution. Then you get a coloured flame which lasts long enough to examine it properly.

 

The colours come from electrons which have been excited dropping back down to their ground states (or lower excited states). Because the differences in energy levels are different for each ion, the sizes of the "drops" the electrons make is characteristic of the ions and so is the wavelength of the photons released. For more information, look up atomic emission.

Isopropyl, ethanol, or other?

 

Oh, and thanks for the explanation.

[Mr Skeptic]

Oh that is even better. Ask a chem teacher, they would probably be glad to help. The lab should have Bunsen burners, ion solutions, and platinum loops for holding some solution in the flame.

[MDJH]

Oh that is even better. Ask a chem teacher, they would probably be glad to help. The lab should have Bunsen burners, ion solutions, and platinum loops for holding some solution in the flame.

What is even better? Can't quite tell what you're referring to there. o.o

 

But yeah, I'll probably ask the chemistry instructors at my university about this kind of stuff after the weekend. Not sure if they'd let me use their bunsen burners, ion solutions, and "platinum loops" (I haven't seen them at my university and am not even sure what they are) for a for-fun experiment though.

[hermanntrude]

the alcohol is ethanol usually.

[Mr Skeptic]

What is even better?

 

Access to various chemistry labs and the stuff in them, rather than trying it with a badly contaminated wood fire. Even if for some reason the teacher won't let you (note: you need a lab partner to use the lab), almost certainly one of the chemistry labs will be about the flame test and you could join that class for a day.

[MDJH]

Access to various chemistry labs and the stuff in them, rather than trying it with a badly contaminated wood fire. Even if for some reason the teacher won't let you (note: you need a lab partner to use the lab), almost certainly one of the chemistry labs will be about the flame test and you could join that class for a day.

Actually, we did the flame test for a some metals as part of one of the labs during intersession chemistry. But those labs were generally unpleasant, (and I wouldn't want to do any more chemistry courses) I was watching from a distance, and it just doesn't feel the same as it would if I was doing it on my own spare time and at my own pace.