Sciencemadness Discussion Board

Basic stannous nitrate, Sn3(OH)4(NO3)2

plante1999 - 27-5-2012 at 07:13

I read that this compound is made when copper,tin, sulphur and potassium nitrate are in presence together, from what I read it is an energetic compound. Did someone already made this compound? What is it's characteristics? I suppose many incident happened with it in gunpowder manufacture in the past, since all these chemicals where present!

Adas - 27-5-2012 at 08:01

I think better method would be exposing Sn powder to copper nitrate (solution).

AndersHoveland - 16-3-2013 at 13:49

This is an obscure novelty explosive, which is very easy to prepare. (if anyone was wondering, the word "basic" in the compound name merely implies that this is the alkaline form of the salt.)

Basic stannous nitrate, with the formula Sn3(OH)4(NO3)2, is a white crystalline substance which is slowly oxidized upon exposure to air, and partially decomposes in pH nuetral water. It is a high explosive, detonating when strongly rubbed, hit with a hammer, or heated above 100 °C. Thermal decomposition proceeds at 125 °C, resulting in formation of SnO2, nitric oxide, and water.

The salt may result when elemental tin (Sn) foil (not common aluminum foil) is reacted with a solution of copper nitrate to form a precipitate that is a sensitive explosive when dried. When detonated with heat or friction, it gives off sparks. It can also be made by using cold, very dilute nitric acid to dissolve tin, then adding some sodium carbonate (baking soda might work instead), but not enough sodium carbonate to cause to cause the expected precipitation of stannous (tin II) carbonate.

Solutions of tin(II) sulfate can be formed by reaction of copper(II) sulfate with metallic tin. The tin(II) sulfate then reacts with sodium carbonate to form tin(II) carbonate (ammonia could probably be used instead, I do not think ammonia solubilizes tin precipitates like it does with some other transition metals). The SnCO3 precipitates out as a solid from the solution. The solid tin carbonate, SnCO3, reacts with dilute nitric acid to form solutions of Sn(NO3)2, which are reasonably stable. However, attempting to evaporate the solutions to dryness results in decomposition, which can in some instances be violent. The decomposition products are mainly SnO2, nitrous oxide, and hydroxylamine, with other oxides of nitrogen also produced.


At the Royal Powder Works at Spandau, Prussia, frequent ignition of the powder at a certain stage of the process led to an examination of the machinery, when it was found that where, at certain parts, bronze pieces which were soldered were in constant contact with the moist powder, the solder was much corroded and in part entirely destroyed, and that in the joints had collected a substance which, on being scraped out with a chisel, exploded with emission of sparks. It was suspected that the formation of this explosive material was in some way connected with the corrosion of the solder, and the subject was referred for investigation to Rudolph Weber, of the School of Technology in Berlin. The main results of his investigation appeared in Journal für Praktische Chemie are given below:

The explosive properties of the substance indicated a probable nitro-compound of one of the solder metals (tin and lead), and as the lead salts are more stable and better understood than those of tin, it was resolved to investigate the latter, in hope of obtaining a similar explosive compound. Experiments on the action of moist potassium nitrate on pure tin led to no result, as no explosive body was formed. Stannous nitrate, Sn(NO3)2, formed by the action of dilute nitric acid on tin, has long been known, but only in solution, as it is decomposed on evaporating. By adding freshly precipitated moist brown stannous oxide to cool nitric acid of specific gravity 1.20, as long as solution occurred, and then cooling the solution to -20°, Weber obtained an abundance of crystals of the composition Sn(NO3)2•(20)H2O. They resemble crystals of potassium chlorate. They cannot be kept, as they liquefy at ordinary temperatures. An insoluble basic salt was obtained by digesting an excess of moist stannous oxide in solution of stannous nitrate, or by adding to a solution of stannous nitrate gradually in small portions, with constant stirring, a quantity of sodium carbonate solution insufficient for complete precipitation.

Thus obtained, the basic salt is a snow-white crystalline powder, which is partially decomposed by water, and slowly oxidized by long exposure to the air, or by heating to 100°. By rapid heating to a higher temperature, as well as by percussion and friction, it explodes violently, giving off a shower of sparks. This compound is also formed when a fine spray of nitric acid (sp. gr. 1.20) is thrown upon a surface of tin or solder. It is also formed when tin or solder is exposed to the action of a solution of copper nitrate, and thus formed presents the properties already described.

In this, then, we have a probable cause of the explosions occurring in the powder works; but the explanation of the formation of the substance is wanting, as potassium nitrate was shown not to give an explosive substance with tin. A thin layer of a mixture of sulphur and potassium nitrate was placed between sheets of tin and copper foil, and allowed to stand, being kept constantly moist. After a time the copper was found to have become coated with sulphide, while the tin was largely converted into the explosive basic nitrate. The conditions are obviously the same as those found in the powder machinery, where bronze and tin solder are constantly in contact with moist gunpowder. The chemical action is probably this: the sulphur of the powder forms, with the copper of the bronze, copper sulphide; this is oxidized to sulphate, which reacts with the niter of the powder, forming potassium sulphate and copper nitrate; the latter, as shown above, then forms with the tin of the solder the explosive basic nitrate, which, being insoluble, gradually collects in the joints, and finally leads to an explosion.

[Edited on 16-3-2013 by AndersHoveland]

Formatik - 16-3-2013 at 23:46

Sn3(OH)4(NO3)2, tin(II)hydroxide nitrate is described in Gmelin. The substance is unstable and first becomes yellow then explodes lightly in storage after a couple of months. Heating to 125 C causes explosive decomposition to SnO2, NO, NO2 and N2O. The compound is more impact sensitive than lead azide and lead styphnate, but less sensitive towards friction. It is said to be very stable towards ignition by sparks. It is barely soluble in cold H2O, hot water causes partial solvation and hydrolysis. A lesser pure form (less pure than the method of Weber using cooling) of it is said to form from adding solid NaHCO3 in small portions to SnO in dilute nitric acid.