DSC_JN
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RFNA + Furfuryl Alcohol
Hello,
Im new on this forum.
I am a member of a amateur rocket group, called Danish Space Challenge (DSC).
We are currently designing an experimental rocket engine, for which we will concentrated nitric acid as an oxidizer and furfuryl alcohol as fuel.
We are of course taking proper safety precautions (respirators, protective clothing, compatible gloves/boots).
We are currently concentrating 53% Nitric acid to ~99% Nitric Acid by boiling it with concentrated sulfuric acid.
Within Danish law we have permission to produce, store and use all relevant chemicals (in case anyone is wondering).
Do you guys know any good methods for characterising Nitric Acid?
Our product is yellowish and have a density of 1.55 kg/l at 5 degrees C.
This is slightly above the maximum theoretical density of 1.54kg/l.
We suspect that the slightly increased density may be due to Nitric Oxides, but how can we determine the amount of Nitric Oxides present without fancy
equipment?
Could we gain an estimate of the amount of nitric oxides, by using vacuum to remove the fumes and determine the density for the white fuming nitric
acid left behind?
We have of course also tested the hypergolicity of the acid with furfurylic alcohol and have measured an ignition time of ~35ms. Does anyone here know
of methods that can be used to speed up the ignition?
Link to hypergolic reaction (facebook post 30. marts 2015), for your viewing pleasure.
https://www.facebook.com/DanishSpaceChallenge
Kind regards,
Jeppe Nielsen, DSC
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brubei
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distillation through urea under vaccum (40-50°C) prevent the formation of nitric oxides
KMno4 will oxyde NO2 to NO3- wich may lead do titration by decoloration of the purple solution
[Edited on 3-4-2015 by brubei]
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blogfast25
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Quote: Originally posted by DSC_JN  | Our product is yellowish and have a density of 1.55 kg/l at 5 degrees C.
This is slightly above the maximum theoretical density of 1.54kg/l.
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Are you sure that difference of 1.54 and 1.55 is actually significant? How did you determine that density? BTW, most sources have the density of pure
nitric acid as 1.51 g/cm<sup>3</sup>.
Simple acid/base titration should also tell you the weight % strength of your HNO<sub>3</sub>.
Also, accurately check the boiling point of your acid.
[Edited on 4-4-2015 by blogfast25]
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DSC_JN
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You bring up a good point. After having examined the used glassware (measuring cylinder 250ml:5ml +-2ml at 20 C) the value of 1.55 is within the
expected deviation. Therefore I cannot rule out that we have 99.9% pure nitric acid, except for the urine like darkish yellow color.
Density was originally determined by using a weight with 4 significant digits and determining weight at 50ml, 100ml, 150ml, 200ml and 250ml
respectively. The density was calculated as the slope of the linear regression to the points. R^2=0.96
Still, we would like to know the nitric oxide content of the acid.
Kind regards,
Jeppe Nielsen, DSC
Edit: 1.51 g/ml is typically the max density at 20 degrees C, however as our nitric acid is stored at 5 degrees C, the corrosponding max density is
1.54. Inhibited Red fuming nitric acids such as IRFNA IIIA (14% NO2) typically have densities of atleast 1.6-1.7 g/ml, which is why we expect that our
Nitric Acid may contain nitric oxides.
[Edited on 4-4-2015 by DSC_JN]
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blogfast25
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| Quote: Originally posted by DSC_JN | You bring up a good point. After having examined the used glassware (measuring cylinder 250ml:5ml +-2ml at 20 C) the value of 1.55 is within the
expected deviation. Therefore I cannot rule out that we have 99.9% pure nitric acid, except for the urine like darkish yellow color.
Density was originally determined by using a weight with 4 significant digits and determining weight at 50ml, 100ml, 150ml, 200ml and 250ml
respectively. The density was calculated as the slope of the linear regression to the points. R^2=0.96
Still, we would like to know the nitric oxide content of the acid.
Kind regards,
Jeppe Nielsen, DSC
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For best results with density use a proper pycnometer. Or, if you're willing to measure on 50 or 100 ml, use a calibrated (Class A) Volumetric Flask,
which is much more accurate than a measuring cylinder.
The value of R squared by itself means very little, BTW. Combined with a good idea of Standard Deviation it can provide confidence intervals on
predicted values, on its own it's fairly meaningless.
Poster 'brubei' is probably right about KMnO<sub>4</sub> being able to oxidise NO<sub>2</sub> to nitrate. To turn that
principle into a working method (a titration) may not be easy though.
[Edited on 4-4-2015 by blogfast25]
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DSC_JN
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Thanks for the input.
The measuring cylinder was used as it was the only useful glassware we had available.
We can easily spare a couple of liters for experiments, as we can produce around 1-2kg an hour in continuous production with our current setup.
Kind regards,
Jeppe Nielsen, DSC
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