Sciencemadness Discussion Board - Iron III Nitrate Fe(NO3)3 synthesis ?

I found an interesting equation on the net in making Iron III nitrate with some easily found chemicals. Fe2O3 + 6 KNO3 = 2 Fe(NO3)3 + 3 K2O Can any one tell me if this reaction between Iron oxide and Potassium Nitrate this true. And if it is true, is the Iron III Nitrate i get Anhydrous ? or some other hydrates ?

Thanks.

Also, how shall i do this ? Fe2O3 is not even soluable in water.. and.. K2O will react with Water.. umm.. and how shall i purify the Iron III Nitrate ?

Well i do have Acetone that dissolves it but can any one tell me if KOH is soluable in Acetone ? thx.

[Edited on 2-3-2013 by KonkreteRocketry]

The reaction you suggested doesn't work. Fe2O3 will not dissolve in any solvent without reacting with it and K2O is far too basic to coexist with Fe(NO3)3 (which is quite acidic).

The (as far as I know) only reliable route to Fe(NO3)3 is dissolution of iron in nitric acid/nitrogen oxides.

Edit: I see that this is posted in the Energetic Materials section, so you're probably thinking of using Fe(NO3)3 as an oxidiser. The hydrous salt will melt and decompose, releasing water and nitrogen oxides, and the anhydrous salt is difficult to prepare on a small scale, let alone large. You should forget about using it as an oxidiser and stick to KNO3.

[Edited on 2-3-2013 by weiming1998]

Motherload - 2-3-2013 at 06:44

I don't believe that reaction will proceeded in aqueous conditions at all..
May happen if a stoicmetric mix was ignited or heated. Water can not be used at all to separate K2O from the mix as KOH will form and will react with Fe(NO3)3 converting it to a oxide or hydroxide and both are soluble in Alcohol and Acetone
FeCl3 might react with NH4NO3 in an alcoholic solution.

KonkreteRocketry - 2-3-2013 at 08:13

thank you, but KNO3 have only 40 meh % oxygen and FeN3O9 have almost 60%

weiming1998 - 2-3-2013 at 16:02

thank you, but KNO3 have only 40 meh % oxygen and FeN3O9 have almost 60%

Yes, but the hydrous salt also contains anywhere up to 9 molecules of water per molecule of Fe(NO3)3. It is like pouring water on a pyrotechnic composition. It becomes much harder to light and it will often not burn (there are exceptions). The decomposing salt will also absorb heat, making ignition even harder.

The anhydrous salt is extremely hygroscopic. It is also a reactive nitrating agent. You'll be hard-pressed to keep it anhydrous for long out in the open. It might also react with your fuel in unexpected ways (especially if the fuel is organic).

DraconicAcid - 3-3-2013 at 16:39

I see that this is posted in the Energetic Materials section, so you're probably thinking of using Fe(NO3)3 as an oxidiser. The hydrous salt will melt and decompose, releasing water and nitrogen oxides, and the anhydrous salt is difficult to prepare on a small scale, let alone large. You should forget about using it as an oxidiser and stick to KNO3.

thank you, but KNO3 have only 40 meh % oxygen and FeN3O9 have almost 60%

If that's your only consideration, then switch to water- it's 88% oxygen!

AndersHoveland - 3-3-2013 at 23:01

When not in presence of water, Iron(III) nitrate is a mild lewis acid. It might not give up its water of hydration so easily. (in other words, the nitrate may decompose at the same time the water is released)

KonkreteRocketry - 4-3-2013 at 09:28

Quote: Originally posted by DraconicAcid

thank you, but KNO3 have only 40 meh % oxygen and FeN3O9 have almost 60%

If that's your only consideration, then switch to water- it's 88% oxygen!

but water is neither a nitrate nor an oxidizer, so u can't compare them directly,

but u can compare nitrates to nitrates, chlorates to chlorates, and so on. here KNO3, O took 47% of the mass, while in Fe(NO3)3 oxygen have 60% mass of oxygen, so in same amount of nitrate oxidizers, one have 13% more, so in stoichiometry, Iron III nitrate needs only 95% of weight of KNO3 needed in any pyrotechnical mix. and therefore iron 3 nitrate would be better, u can not compare H2O to nitrates.

Is there any way to convert KNO3 to any other nitrates ?

KonkreteRocketry - 6-3-2013 at 06:32

so, if i put Iron in Dilute nitric acid solution, it would work ?

I can make a nitric acid solution around 10% by making NO2 going into water. I heard nitric acid can have hydrates, so my Iron III Nitrate i get from it will have hydrated too ? And also, i dont have pure iron but i can make Fe2O3 with a 90% Iron, steel anode. can Fe2O3 work with a dilute nitric acid ? will it be hydrated ? thx a lot.

Also i think this equation is correct ?

2Fe + 3Cu(NO3)2 → 2Fe(NO3)3 + 3Cu

but i heard u get Fe(NO3)2 also, so can i use Fe2O3 again here ?

[Edited on 6-3-2013 by KonkreteRocketry]

AJKOER - 6-3-2013 at 07:30

Add NH4NO3 to aqueous Fe(HCO3)3, and slowly heat to concentrate and drive off ammonia and CO2. Add alcohol and let the solution evaporate to hopefully recover Fe(NO3)3 and not Fe(NO3)3.9H2O (the hydrate). No guarantees it will work.

Reactions:

3 NH4NO3 + Fe(HCO3)3 <--> Fe(NO3)3 + 3 NH4HCO3

3 NH4HCO3 --Heat--> 3 NH3 (g) + 3 CO2 (g) + 3 H2O

Do not heat in an open vessel with O2 exposure as it can decompose Fe(HCO3)3 to Fe(OH)3, moving the 1st reaction to the left. To prepare aqueous Fe(HCO3)3, try reacting FeCl3 (note, iron dissolved in Bleach + vinegar makes a contaminated form of a Ferric salt) with aqueous NaHCO3 (preheated to remove O2).

[Edited on 6-3-2013 by AJKOER]

KonkreteRocketry - 6-3-2013 at 07:47

Add NH4NO3 to aqueous Fe(HCO3)3, and slowly heat to concentrate and drive off ammonia and CO2. Add alcohol and let the solution evaporate to hopefully recover Fe(NO3)3 and not Fe(NO3)3.9H2O (the hydrate). No guarantees it will work.

Reactions:

3 NH4NO3 + Fe(HCO3)3 <--> Fe(NO3)3 + 3 NH4HCO3

3 NH4HCO3 --Heat--> 3 NH3 (g) + 3 CO2 (g) + 3 H2O

I don't have NH4NO3, do u know if Fe2O3 + Cu(NO3)2 can work ?

AndersHoveland - 6-3-2013 at 07:55

I think in this case it would probably form an ammonia complex with the iron instead. Remember, there is no water here to complex to the Fe+3 ions, so they will be a fairly strong lewis acid.

If found this quick explanation somewhere else:

Quote:

Why doesnt iron form ammonia complexes?

Ammonia can function as a Bronsted-Lowry base (proton acceptor) as well as a Lewis base (ligand). In the case of aqueous iron solutions, the greater tendency is for the ammonia to accept protons from the water molecules that are binded to the iron ion:

[Fe(H2O)6]^+3 + 3 NH3 <=> [Fe(H2O)3(OH)3] + 3 NH4^+1

Another way to think of it is like this: the iron ion is itself a Lewis acid, so it reacts with water prior to the addition of ammonia to form hydronium ions:

Fe^+3 + 2 H2O --> Fe(OH)^+2 + H3O^+1

So when you add the ammonia, it reacts more readily with the hydronium ions than with the iron ions.

In response to your follow-up question...and please understand that this is just a guess (albeit a somewhat educated one)...my suspicion is that the Cu^+2 ion is a weaker Lewis acid than the Fe^+3 ion, resulting in fewer hydronium ions in solution and a greater tendency for the ammonia in solution to replace water molecules as ligands. Again, this isn't guaranteed to be correct; I couldn't find any information online regarding the comparative strength of Cu^+2 ions and Fe^+3 ions as Lewis acids.

I do not think you would be able to drive out the ammonia without causing decomposition of the nitrate. (although I am not entirely sure) You could drive off the ammonia by adding water, but then it would just form the hydrate.

AJKOER - 6-3-2013 at 10:30

Using Copper nitrate, again more likely just a hydrate, Fe(NO3)3.9H2O:

6 Cu(NO3)2 + 4 Fe(HCO3)3 (aq) --> 3 Cu2(OH)2CO3 (s) + 4 Fe(NO3)3 + 9 CO2 + 3 H2O
-----------------------------------------

In a horizontal tube, 1st packed with Cu(NO3)2, then a drying agent and Fe2O3, where both Cu(NO3)2 and Fe2O3 are being heated in a sealed tube (as any thermal decomposition may reform Fe(NO3)3 on cooling). Reactions:

6Cu(NO3)2 --> 6 CuO + 12 NO2 + 3 O2

2 Fe2O3 + 3 O2 + 12 NO2 --> 4 Fe(NO3)3

more difficult, but perhaps anhydrous Fe(NO3)3.

[Edited on 6-3-2013 by AJKOER]

KonkreteRocketry - 6-3-2013 at 10:49

Using Copper nitrate, again more likely just a hydrate, Fe(NO3)3.9H2O:

6 Cu(NO3)2 + 4 Fe(HCO3)3 (aq) --> 3 Cu2(OH)2CO3 (s) + 4 Fe(NO3)3 + 9 CO2 + 3 H2O

Is it possible to take the hydrate out of Iron III Nitrate nona hydrate ?

DraconicAcid - 6-3-2013 at 11:34

Using Copper nitrate, again more likely just a hydrate, Fe(NO3)3.9H2O:

6 Cu(NO3)2 + 4 Fe(HCO3)3 (aq) --> 3 Cu2(OH)2CO3 (s) + 4 Fe(NO3)3 + 9 CO2 + 3 H2O

Is it possible to take the hydrate out of Iron III Nitrate nona hydrate ?

I doubt it. The Merck Index says it melts at 43oC and decomposes under 100oC. While it might lose water at high temperature, it's more likely to lose nitric acid and form hydroxides.

weiming1998 - 7-3-2013 at 03:05

Using Copper nitrate, again more likely just a hydrate, Fe(NO3)3.9H2O:

6 Cu(NO3)2 + 4 Fe(HCO3)3 (aq) --> 3 Cu2(OH)2CO3 (s) + 4 Fe(NO3)3 + 9 CO2 + 3 H2O

Is it possible to take the hydrate out of Iron III Nitrate nona hydrate ?

Maybe something like thionyl chloride might work, but I doubt it, as it will most probably oxidise and/or form nitrosyl compounds with nitrates. Even if it does work, I would not go through the troubles of acquiring thionyl chloride for a bit of a pyrotechnic oxidising agent. Oxygen content is not everything, and KNO3 should be far more effective when used as an oxidising agent compared to anhydrous Fe(NO3)3. The hydrous iron (III) nitrate won't even burn with fuels; it simply decomposes.

AJKOER - 15-3-2013 at 05:43