[Vargulf]

Hi,
I'm not sure if the reaction I assumed is right. Na8Al6Si6O24S4+ 8HCl ->4H2S+ NaCl+ Al6Si6O24
Can you please check it and if it's wrong explain me how to figure out the reaction?
Thank you very much. Just say you I'm always doubting myself when it comes to predicting reactions.

[chenbeier]

No double post please.
The equation is not balanced. Check all atoms right and left.
Consider that probably also aluminium will be dissolved.

[billnotgatez]

Just some interesting information that I happened to find with GOOGLE.
The compound in the original post is highlighted in red.


Advances in Materials Physics and Chemistry, 2015, 5, 171-184

2.1. Ultramarine Pigment
A standard ultramarine blue pigment produced by Nubiola Pigmentos S.L. was used. Ultramarine pigment compositions are based on the crystal chemistry of the royal blue Sodalite mineral Lazurite [Na₆Ca₂Al₆Si₆O₂₄(Sn,SO₄)₂].
Some compositions suggested for synthetic ultramarine blue pigments include Na₈Al₆Si₆O₂₄S₄ or Na₇Al₆Si₆O₂₄S₃ [19], although actual compositions are usually complicated by minor amounts of impurities from starting materials.

[Vargulf]

Thank you for your fast answer. I'm sorry that I double posted. I did it on accident and don't know how to delete it.
Is this new reaction right? I don't know what you mean with that aluminium will be dissolved. Do you mean it like this?
Na8Al6Si6O24S4(s)+ 8HCl(l) -> 4H2S(g)+ 8NaCl(aq)+Si6O24(s)+6Al(aq)

Billnotgatez thank you for your effort. I know that the ultramarine pigment is not completely pure.
My task was to show the reaction of ultramarine blue with hydrochloric acid and this is the best I'm able to do.
I also read that ultramarine blue can also have the composition Na7Al6Si6O24S3.
I think it's almost impossible to show the real reaction, so I kept it theoretical.

[Arkcon]

OK.  The reaction isn't balanced, the same amounts of the atoms must be on both sides.  We don't talk about reactions that are unbalanced, just like we don't drive a car with 3 wheels.

The reaction must make sense, and this is a little bit complicated.  For example:

2 Na + 2 H₂O  2 NaOH + H₂

If I write:

Na + H₂O NaO + H₂

That's not a new discovery, that's something I made up that can't exist.

Na8Al6Si6O24S4+ 8HCl ->4H2S+ NaCl+ Al6Si6O24

Balanced, this might mean something.  We should try to understand what happens for example, does soluble sodium chloride result?  Does hydrogen sulfide evolve?  We can see those, and if we don't, then we don't write the reaction that way.

Na8Al6Si6O24S4(s)+ 8HCl(l) -> 4H2S(g)+ 8NaCl(aq)+Si6O24(s)+6Al(aq)

Does pure aluminum metal dissolve in water?  If not, then it doesn't as the product of a reaction.

[Vargulf]

I'm pretty sure about the hydrogen sulfide result, but I'm not sure with what the chloride ion reacts with. I think the ion will either react with sodium or with aluminum. In a normal compound I would say that the chloride ion will react with sodium, because sodium is futher up in the reactivity series than aluminum. I'm not sure with this compound through, because the Na ions are (like the polysulfide ions) in "cages", make up of the rest of the compound.
Pure Aluminum metal does not dissolve in water you're right.

[Borek]

In a normal compound I would say that the chloride ion will react with sodium, because sodium is futher up in the reactivity series than aluminum.

Seems like you are forgetting about the fact sodium in the compound is already in the oxidized, ionic form (so it will not take part in any redox reaction, governed by the reactivity series).

[Vargulf]

Thank you for your help. So hydrogen sulfide and aluminum chloride result from this reaction, right? The only problem would be that there are not enough aluminum atoms in comparison to the sulfur atoms. Or are not all sulfur atoms reacting, because they are ionized?