I have tried to do some further research on these reactions online, but with no luck. Maybe someone here knows if these reactions actually make sense
and whether or not they will and work?
My first question is about the reaction of sodium nitrate with hydrogen. This reaction goes on when Drāno Crystals are cleaning your drain, and
works even better if you add extra aluminium (like certain pop cans) to the mix. While I was reading about how the drain cleaner functioned, I learnt
that the sodium nitrate is in the mixture to "catch" the hydrogen in order to prevent a explosion or fire hazard. Unsure of what the text meant by
"catching" the hydrogen, I did a little more research and found this reaction:
2 NO3- + 9 H2 → 2 NH3 + 6 H2O
It states that the nitrate ion and hydrogen react to form ammonia and water. But in a sense, this equation is incomplete because it doesn't state what
becomes of the sodium ions. And yes, I realize that you could go on about the fact that the sodium ions don't react in any way because they are in
solution, but there still has to be some negative ions somewhere to counteract their positive charge, and to form an ionic compound if all the water
where to evaporate, right? So I came up with this overall reaction:
NaNO3 + 4 H2 → NH3 + 2 H2O
I figured that hydroxide would be the only available negative ion that could have formed an ionic compound with the sodium ions. So is this reaction
correct, or did I get something wrong?
My next question concerns the reaction of ferrous disulphide (pyrite) and ferric chloride. Someone mentioned this reaction in another topic:
The user also stated that he was unsure about this reaction. Could I get any confirmation on it? Assuming it is true, and the source of my ferric ions
where from ferric chloride (like I mentioned before) would this reaction occur?
Another user mentioned that he found ferrous disulphide notoriously difficult to dissolve in strong acids, so I am going to assume that if this
reaction does work, it will be very slow. Despite that, I would still like to know if it works at all, because if it does, this may be a useful method
of creating both sulphuric acid and hydrochloric acid. One last question, if the reaction works, would most of the hydrogen chloride dissolve right
away to make hydrochloric acid, or would it just escape as a gas?
[Edited on 21-8-2013 by Chemistry_Keegan]Justin Blaise - 20-8-2013 at 22:13
For the first equation, I like the following a little better:
NO3- + 4H2 --> NH3 +2H2O + OH-
That being said, just because it looks good on paper doesn't mean that it necessarily works this way, but at least the charges balance now.elementcollector1 - 20-8-2013 at 22:32
I'm not quite sure hydrogen could react with nitrates in solution - hydrogen is insoluble in just about everything.
Sulfides and strong acids react to give H2S, a toxic and sometimes-explosive gas that is responsible for the smell of rotten eggs. I'm not sure about
rate of reaction, but I do know that H2S is poorly soluble in water.AndersHoveland - 20-8-2013 at 22:49
No, hydrogen does not reduce nitrate, not in solutions at ambient temperatures. Nitrate will be reduced, however, when in the presence of metals being
attacked by acid. Hydrochloric acid on zinc is a typical such reducing agent. Sodium hydroxide on aluminum will also work.
The Drano cleaner with NaNO3, NaOH and Al-prills has the NaNO3 added to assure that no hydrogen is formed. Without the NaNO3, the Al-metal reduces the
hydroxide, leading to formation of H2 and aluminate ion. When NaNO3 is present, then the aluminium has an alternative for its reaction, it likes the
nitrate ions more than the hydroxide ions. In this way, it is assured that no hydrogen gas is released, but ammonia is formed instead. So, it is not
that first hydrogen is formed and that this in turn reacts with nitrate. The nitrate prevents formation of free hydrogen gas.
I have done some experiments with pyrite and I have found that this material is remarkably resistant to chemical attack. I treated it with conc. HCl,
conc. HNO3 and with mixes of H2O2 and acid. It does react, but only very slowly. At room temperature it takes days or even weeks to dissolve a chunk
of FeS2. When the material is heated, then the reaction goes faster, but then it still takes hours at least.Fantasma4500 - 21-8-2013 at 07:48
NaNO3, NaOH + Al > NH3 ??
that is a absolute sure must try, always wondered why the hell they would add NaNO3 to NaOH
this could be a very interesting way to make NH4OH with easily accessible chemicals, KNO3 from ground and ashes
NaOH from wood asheswoelen - 21-8-2013 at 11:11
NaOH is not present in wood ashes. Wood ashes contain carbonate, not hydroxide. The old way of making hydroxide was by very strongly heating CaCO3,
such that CO2 is driven off and CaO remains behind. This was dissolved in water and reacted with a solution of Na2CO3 or K2CO3. Calcium carbonate
precipitated and NaOH or KOH remained in dilute solution, which could be boiled down to get higher concentration. The hydroxide thus produced was not
very pure, it always contained quite some calcium-contamination. Nowadays there are much better processes for making hydroxides, based on electrolysis
of aqueous solutions of NaCl or KCl.Chemistry_Keegan - 21-8-2013 at 14:16
So, based on what some of you guys are saying, would this overall reaction make more sence:
I don't quite see the point in generating NH3 in the context of Draino, though. It's a weak base (and there's already a strong one in there) and it
stinks. And with so much water around there can't be much bubbling either, ammonia being so water soluble...subsecret - 21-8-2013 at 15:26
It might depend on how concentrated the ammonia becomes. I've heard that concentrated ammonia solutions can be pretty nasty. It also depends on what
sort of plumbing fixture it's being used in. A sink will have a smaller volume of water than a toilet, and so on. Let's say that a toilet has about
one liter of water sitting in the bottom...This would require about 18 moles of dissolved ammonia to form a saturated solution...Which, based on the
reaction above, would require 30 moles of NaOH. This would come out to 1199.91 grams of NaOH...plus the other things in the drain opener. Also, not
all of the ammonia would dissolve, and releasing that much ammonia into a bathroom might be dangerous.. I wouldn't want to pour a kilogram of drain
opener down my drain...
Do the Draino bottles say something along the lines of "With the extra punch of ammonia!" blogfast25 - 22-8-2013 at 04:51
@Awesome:
If you'd get bubbles of NH3, you'd basically be gassing yourself. Trust me, I sell a lot of 33 % NH3 and the slightest spill is a cause for temporary
evacuation and immediate mopping up: it's extremely pungent and really 'catches' your breath.
