[dan0512]

Hey guys, I'm writing a report on nitric acid for school, and from my research I've found out that the first syntheses were done by heating potassium nitrate (KNO3) together with hydrated copper sulfate (CuSO4 * 5H2O), and (or?) Alum (CuSO4 * 5H2O - KAl(SO4)2*12H2O).

It is also mentioned that melanterite (FeSO4 * 7H2O) could be used as well.

Unfortunately, there is not much information regarding the reactions, so I'd be glad if someone could help me out with the chemical equations - I could probably work out some theoretical products (aside from HNO3 ), but I wouldn't know if they're right or not . I'm just a noob when it comes to chemistry, so any help would be appreciated.

dan

[Arkcon]

What do you think you'll need to make nitric acid out of potassium nitrate?  What does potassium nitrate have that nitric acid has, and what does it lack?  And how can you get it from the other chemicals you mentioned?  *Hint* that last question is a tough one.

PS. wrong formula for alum

[dan0512]

Ohh, yuck - darn copy - paste.. it should be KAl(SO4)*12H2O.

Well to make HNO3 out of KNO3, you obviously need hydrogen which is present in all the minerals - I really have no idea how the rest of the elements present in the minerals will react.

dan

[Arkcon]

You're close, read more on how nitric acid was first made, what were those people really doing, and who were they, what was their time period, what sort of equipment they were using, how'd they collect their nitric acid, things like that.  You'll need to pad this report out, any way.

[Borek]

Ohh, yuck - darn copy - paste.. it should be KAl(SO4)*12H2O

Still wrong - although closer

[dan0512]

Well, I've done quite a bit of research and that's the only information I can get regarding the synthesis. These methods date back to the 9th and 12th century.

I suppose it could probably run this way:

5KNO3 + CuSO4 * 5H2O ---> 5HNO3 + 5KOH + CuSO4

I have absolutely no idea whether the potassium will react to potassium oxide (K2O), or to potassium hydroxide (KOH).

dan

[Arkcon]

Your reaction is not a very good one.  Although water contains hydrogen atoms, it is unlikely to surrender one to make acid -- else acid would be much more common in the world, there's a very pertinent intermediate step, can you find it given the similarites of your reactants?  What were people doing in the 9th and 12th centuries?  That could be referred to as almost like chemistry?  What equipment did they use? 

[dan0512]

Well, they were alchemists doing a bunch of experiments, probably trying to turn lead into gold  regarding the tools that they had, probably some devices for distillation and other simple tasks.

I also thought that water wasn't probably going to react with potassium nitrate that way, otherwise you could just put it into tap water, and voila there's your acid. Since KNO3 is a salt it would probably get split into its ions. But my sources don't mention an intermediate step, so I inferred that "somehow" it must react to nitric acid.

I really don't have a clue on what I could throw in the mix to make it all work....

dan

[Arkcon]

probably some devices for distillation and other simple tasks.
dan

Work this angle.

[dan0512]

I found this article in Wikipedia:

http://en.wikipedia.org/wiki/Aqua_fortis

It seems the mixture of Salpeter and either of the minerals is heated up and the gas is distilled. I myself can't come up with the equation, it'd be very nice if you could help me out with it, since I can't come up with anything after some hours of thinking. Please!

How does:

KNO3 + CuSO4 * 5H2O ---> HNO3 +..

dan

[ARGOS++]

Dear Dan0512;

Could this be of help to you?:  "Alchemy” (page 274)


Good Luck!
                    ARGOS⁺⁺

[dan0512]

So I take that when you heat the ingredients, the following happens:

KNO3 + CuSO4 * 5H2O -> KNO3 + CuO + H2SO4 + 4H2O

and then

H2SO4 + KNO3 -> HNO3 + KHSO4

Analog with alum and iron sulfate?

is that correct?

dan

Dear Dan0512;

Could this be of help to you?:  "Alchemy” (page 274)


Good Luck!
                    ARGOS⁺⁺

[ARGOS++]

Dear Dan0512;

At least the first Reaction we have to rewrite, because “distillation”/decomposition was at that time done at temperatures higher then 100°C.

A.)   CuSO₄          ------>   CuO  +  SO₃
B.)   SO₃   + H₂O   ------>   H₂SO₄ 

Do you agree with me?

Good Luck!
                    ARGOS⁺⁺