Potassium nitrate, effect

Fig. 10 - Hydrated baryta + potassium nitrate effect of stirring.

Potassium nitrate anticatalysed nitration in nitric acid (the solutions used also contained 2-5 mol 1 of water) but the effect was small in comparison with the corresponding effect in nitration in organic solvents ( 3.2.3 4), for the rate was only halved by the addition of 0-31 mol 1 of the salt. As in the case of the addition of sulphuric acid, the effect was not linear in the concentration of the additive, and the variation of k j with [KNOgj/mol 1 " was similar to that of with [H2SO4]/ mol 1. ... 

The effect of potassium nitrate on the rate arises in a similar way. The concentration of nitrate ions in concentrated nitric acid is appreciable, and addition of small quantities of nitrate will have relatively little effect. Only when the concentration of added nitrate exceeds that of the nitrate present in pure nitric acid will the anticatalysis become proportional to the concentration of added salt. 

TABLE 3.4 The effects of potassium nitrate on rates of nitration in nitromethane... 

The addition of water depresses zeroth-order rates of nitration, although the effect is very weak compared with that of nitrate ions concentrations of 6x io mol 1 of water, and 4X io mol 1 of potassium nitrate halve the rates of reaction under similar conditions. In moderate concentrations water anticatalyses nitration under zeroth-order conditions without changing the kinetic form. This effect is shown below (table 3.5) for the nitration of toluene in nitromethane. More strikingly, the addition of larger proportions of water modifies the kinetic... 

The highly exothermic nature of the butane-to-maleic anhydride reaction and the principal by-product reactions require substantial heat removal from the reactor. Thus the reaction is carried out in what is effectively a large multitubular heat exchanger which circulates a mixture of 53% potassium nitrate [7757-79-1/, KNO 40% sodium nitrite [7632-00-0], NaN02 and 7% sodium nitrate [7631-99-4], NaNO. Reaction tube diameters are kept at a minimum 25—30 mm in outside diameter to faciUtate heat removal. Reactor tube lengths are between 3 and 6 meters. The exothermic heat of reaction is removed from the salt mixture by the production of steam in an external salt cooler. Reactor temperatures are in the range of 390 to 430°C. Despite the rapid circulation of salt on the shell side of the reactor, catalyst temperatures can be 40 to 60°C higher than the salt temperature. The butane to maleic anhydride reaction typically reaches its maximum efficiency (maximum yield) at about 85% butane conversion. Reported molar yields are typically 50 to 60%. 

Quantitatively, sulfur in a free or combined state is generally determined by oxidizing it to a soluble sulfate, by fusion with an alkaH carbonate if necessary, and precipitating it as insoluble barium sulfate. Oxidation can be effected with such agents as concentrated or fuming nitric acid, bromine, sodium peroxide, potassium nitrate, or potassium chlorate. Free sulfur is normally determined by solution in carbon disulfide, the latter being distilled from the extract. This method is not useful if the sample contains polymeric sulfur. 

Helt, J.E. and Larson, M.A., 1977. Effects of temperature on the crystallization of potassium nitrate by direct measurement of super-saturation. American Institution of Chemical Engineers Journal, 23(6), 822. 

Naturally, the flux employed will depend upon the nature of the insoluble substance. Thus acidic materials are attacked by basic fluxes (carbonates, hydroxides, metaborates), whilst basic materials are attacked by acidic fluxes (pyroborates, pyrosulphates, and acid fluorides). In some instances an oxidising medium is useful, in which case sodium peroxide or sodium carbonate mixed with sodium peroxide or potassium nitrate may be used. The vessel in which fusion is effected must be carefully chosen platinum crucibles are employed for... 

Reagents. Supporting electrolyte. For chloride and bromide, use 0.5 M perchloric acid. For iodide, use 0.1M perchloric acid plus 0.4M potassium nitrate. It is recommended that a stock solution of about five times the above concentrations be prepared (2.5M perchloric acid for chloride and bromide 0.5M perchloric acid + 2.0A f potassium nitrate for iodide), and dilution to be effected in the cell according to the volume of test solution used. The reagents must be chloride-free. 

It follows also that the actual rate of burning of safety fuse depends on the ambient pressure. Indeed, if the pressure is reduced to less than about a fifth of an atmosphere the burning ceases altogether. In deep mines the extra pressure can be sufficient to give an increase in burning speed of safety fuse. Compared with the effect of pressure other influences on the burning speed are small. Temperature has little effect and humidity also has little effect unless the fuse is kept for a prolonged period at a humidity sufficient to cause deliquescence of the potassium nitrate in the core. 

Heating the bis(trichloromethyl)benzene with potassium nitrate, selenium dioxide or sodium chlorate to effect conversion to the bisfacyl chloride) led to eruptions at higher temperatures, and was too dangerous to pursue. 

Catalytic elfects on the thermal decomposition and burning under nitrogen of the nitrate were determined for ammonium dichromate, potassium dichromate, potassium chromate, barium chloride, sodium chloride and potassium nitrate. Chromium(VI) salts are most effective in decomposition, and the halides salts during burning of the nitrate [1]. The effect of chromium compounds soluble in the molten nitrate, all of which promote decomposition of the latter, was studied (especially using ammonium dichromate) in kinetic experiments [2],... 

Fig. 3.9 The positive effect of nitrogen fertilizer (potassium nitrate) on the growth and productivity of transgenic sprouts (A.) The growth rate, measured as the increase in fresh weight during sprouting.

In the presence of bromide ions the electrode was subject to a drop in potential, (e.g., 1.5 to 5.7 mV at a Br iCl ratio of 2000 3) and to delayed response. A considerable hysteresis effect is also observed in concentrated solutions of chloride when the electrode is used in a 1M chloride solution and then dipped in one that is 0.02 M. Equilibrium is reached only after 10 min. The junction potential is minimised by diluting the test solution with the salt-bridge solution (10% aq. potassium nitrate). 

Fig. 12.12 shows a typical set of flame photographs of a nitropolymer propellant treated with potassium nitrate. From top to bottom, the photographs represent KNO3 contents of 0.68%, 0.85%, 1.03%, and 1.14%. Each of these experiments was performed under the test conditions of 8.0 MPa chamber pressure and an expansion ratio of 1. Though there is little effect on the primary flame, the secondary flame is clearly reduced by the addition of the suppressant The secondary flame is completely suppressed by the addition of 1.14% KNO3. The nozzle used here is a convergent one, i. e., the nozzle exit is at the throat... 

The ultra-micro-hardness of inorganic and organic salts has been measured for 15 substances. These are products usually produced in industrial crystallization. The hardness-force-dependency was examined and data are compared to those from literature. In the case of potassium nitrate a strong direction dependency of the hardness was observed. Also effects of impurities in the crystal lattice were analysed. In the end an attempt has been introduced to calculate the hardness of crystals from a physical model. 

In the case of potassium nitrate the Vickers hardness indentations have not a quadratic shape. This is due to a direction dependent hardness in the crystal lattice of this material. The direction dependency can be explained with an anisotropic effect in the lat-... 

More exotic effects call for more exotic materials, and considerable effort has gone into formulating compositions that are both spectacular in effect and safe to produce and handle. Thus a 30 mm fountain might contain mealed (or hue) gunpowder, potassium nitrate, sulfur, charcoal, antimony trisulhde, barium nitrate, hue aluminium and flitter aluminium with a dextrin binder. This composition is certainly a good deal more complicated than that used for sparklers but is relatively safe to produce and gives a good burst of white sparks. 

Some fountain compositions tend to be oxidant-rich due to the presence of excess potassium nitrate or sometimes various oxalates. The reason for this is to reduce the burning rate and/or to enhance the visual effects. Certainly if gunpowder is considered to be a mixture of fuels (charcoal and sulfur) and oxidant (potassium nitrate) then the maximum rate of burning should coincide with a slightly under-oxidised system. The burning rate is therefore reduced by adding excess nitrate to the system. 

In order to produce satisfactory effects a more powerful oxidiser than potassium nitrate is used together with more calorihc fuels than sulfur or charcoal. In general, for a given oxidation reaction the heat evolved depends upon the oxidiser anion in the following decreasing order. 

The use of pyrotechnic mixtures for military purposes in rifles, rockets, and cannons developed simultaneously with the civilian applications such as fireworks. Progress in both areas followed advances in modern chemistry, as new compounds were isolated and synthesized and became available to the pyrotechnician. Berthollet s discovery of potassium chlorate in the 1780 s resulted in the ability to produce brilliant flame colors using pyrotechnic compositions, and color was added to the effects of sparks, noise, and motion previously available using potassium nitrate-based compositions. Chlorate -containing color-producing formulas were known by the 1830 s in some pyrotechnicians arsenals. 

For a good spark effect, the fuel must contain particles large enough to escape from the flame prior to complete combustion. Also, the oxidizer must not be too effective, or complete reaction will occur in the flame. Charcoal sparks are difficult to achieve with the hotter oxidizers potassium nitrate (KNO 3) -with its low flame temperatures - works best. Some gas production is required to achieve a good spark effect by assisting in the ejection of particles from the flame. Charcoi, other organic fuels and binders, and the nitrate ion can provide gas for this purpose. 

Another important factor is the thermal stability and heat of decomposition of the oxidizer. Potassium chlorate mixtures tend to be much more sensitive to ignition than potassium nitrate compositions, due to the exothermic nature of the decomposition of KCIO 3. Mixtures containing very stable oxidizers - such as ferric oxide (Fe 2O 3) and lead chromate (PbCrO 4) - can be quite difficult to ignite, and a more-sensitive composition frequently has to be used in conjunction with these materials to effect ignition. 

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