From: David Chappell - UK, [EMAIL PROTECTED]
Oh dear, I was trying to avoid the anorak chemical stuff but
it appears I can't so sorry:
Chris Evans said:
<<BP contains Potassium Nitrate (75% by weight), an oxidiser
which will oxidise (rust) steel in the presence of moisture.
Also, one of the products of combustion is
Sulphuric acid, a recognised corrosive which will attack steel.>>
Yes Potassium Nitrate (KNO3 (all my trailing numbers are
subscript :-))is an oxidiser - it is where we get our oxygen
for the combustion of BP to take place. There is absolutely NO
Sulphuric Acid produced by burning Black Powder.
BP is a mixture of one salt (Potassium Nitrate (KNO3) and
two elemental solids; Carbon (C), as charcoal and Sulphur (S)
in the proportion of KNO3 (75%), Carbon (15%) and Sulphur (10%)
For combustion to occur we need fuel (carbon,) oxygen (from
the salt) and an ignition source: (remember the fire triangle?)
- (The Sulphur acts as a catalyst, and to 'clean up' the process)
Chemically, the empirical formula for combustion of Black
Powder can be written as follows:
Heat>
4KNO4 + 7C + 2S = K2CO3 + K2S2 + 3CO2 + 2N2
If we look at the results we find that our solid, (Black Powder)
has produced another solid K2CO3 (Potassium Carbonate) the gases
Carbon Dioxide (CO2), Carbon Monoxide (CO) and Nitrogen (N) and
another solid, Potassium Sulphide (K2S2)
The combustion of BP in an enclosed space (like a gun barrel)
produces a volume of gas some 4000 times greater than the
volume of the solids used.
There is nothing there chemically that CAN produce Sulphuric
Acid, or any other acid!
What is an 'acid'? - It is a substance which produces the
oxonium ion (H30) in water, in other words it releases
Hydrogen Ions in water. 'pH' is the measure of a solution's
acidity (pH is the reciprocal of the Hydrogen Ion in solution)
with 7 being neutral, 1 being the most acidic and 14 being
the most alkaline.
Try something for yourself, put some BP in a glass of water,
shake it up and test it with litmus paper (or Methyl Orange
if you can get it) - you will find no reaction! (try the
same on some powder fouling if you like - you will get the
same result)
The main solid produced (Potassium Carbonate) is very
similar to Calcium Carbonate (Chalk!) and would in fact
react with any acid, which would then be simply neutralised!
Calcium Carbonate is hygroscopic, so if left in a gun barrel
will attract moisture from the atmosphere and you WILL get
rust. Why will you get rust? Well, the iron in the steel
barrel is more reactive than the hydrogen in the water and
therefore 'robs' the water of its oxygen to form rust (iron
oxide) and hydrogen gas. This is the 'normal' process of
rusting and it will occur without the presence of fouling
if no precautions are taken.
All of the products are water soluble, so can be washed
out easily.
(I still stick to using WD40 until I get home :-)
I do hope that this may clear up some misconceptions and
even myths about black powder!
David.
Cybershooters website: http://www.cybershooters.org
List admin: [EMAIL PROTECTED]
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