Making Nitric acid... what did I do wrong?

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dbrick81

Member
Joined
Dec 29, 2007
Messages
17
Location
Delaware
Ok... I tried Steve's recipe for cold production of nitric acid and apparently something went wrong! I followed the recipe to a T (I Think). I dissolved 202g of KNO3 in 100ml of boiling water, then let cool to 75 C, then slowly added 56ml H2SO4 keeping the temp blow 80 C so the the acid would not boil off. When I was done adding the H2SO4 I continued stirring for probably 10 min more. when i cooled to almost room temp I put it in an Ice bath, 20 min later I had a solid bright yellow block in the bottom of my beaker, It looked just like A lemon slushy (and no... I didn't taste it :)) Please help!

David
 
David, everything you stated is normal.
But are you saying that all your solution is a solid block ?

The solid block is K2SO4 but it may have trapped your HNO3

Slow cooling of your solution should yield larger crystals which would reduce mechanical trapping.

If it does not work, you may have to dilute it a bit. Or better yet, cool your solution until your get some crystals at the bottom but do not let it freeze into a block. Filter and repeat above steps until no more crystals form.
 
What concentration was your sulfuric acid?

How accurately did you weigh the KNO3?

Sounds like you ended up with KHSO4, which is more soluble in water than K2SO4, hence the slurry.

Here's the step by step chemistry of the main reaction:

  1. Step 1: KNO3 + H2SO4 --> KHSO4 + HNO3
  2. Step 2: KHSO4 + KNO3 --> K2SO4 + HNO3
  3. Overall Reaction: 2KNO3 + H2SO4 --> K2SO4 + 2HNO3

If everything was accurate, perhaps the solution just needs to settle.

Worst case scenario you can always distill the slurry in a glassware rig.

Steve
 
Steve, Thanks for the fast reply. The acid I'm using is cooked down battier acid so it should be somewhere in the 93-96%. Also I was using a scale that weighs to 1/100 of a gram so I know my measurements were good. As far as solutions for this problem go... could I just bring the mixture up to temp (just before the boiling point of HNO3) and let the solids redissolve, then let it cool very slowly... possibly adding a touch more water, and see if it separates better?

Thanks again,

David
 
Your idea sounds plausible, if it were me I would bring up the temperature and add another 2-4 grams of KNO3 in water and see if the reaction produces a precipitate that separates easier when the temperature is lowered.

Steve
 
Is thier anything else a person can buy (IE lowes,walmart) that has nitric acid? instead of buying from some suppler?

IE. concentrated muratic acid instead of buying HCL from a supplyer and not having to go the homade route.
 
Steve,

I too have had some lemon slush trouble. I am thinking it is the rate it cools. I have poured it into a plastic container as soon as the temperature is low enough but still very hot. Then I put it in the snow outside. 21 degrees F. overnight.

When I pour off there seems to be more still in the slush. I invert on a large funnel with a filter and let drip for a while.

My main concern is this, when I make a batch according to the recipie I get exactly 1/2 the amount I should.
I quadrupled the quantities
400ml water--boil
680g Sodium Nitrate--stir into water untill dissolved, remove from heat.
224ml sulphuric acid (Drain cleaner). added slowly while constantly stiring, no boiling
I get 320ml of Nitric that weighs 138-144 grams per 100ml. I have made 10 batches they all come out the same.
Is there a reason quadrupling each ingredient is wrong?
 
I would suggest cooling at a much slower rate. This will allow bigger crystals to grow and help to keep the crystal front from overtaking the solution. I would also try cooling from the bottom only. You can not get good seperation if you freeze solid because at some point the water and sulfates will crystalize at the same time.

You in any case must not allow to freeze solid or you will end up without seperation.

Remember you are trying to crystalize out of solution the sulfate, you can not get it all - in one cooling anyways, I would cool slowly from the bottom only and I would have a couple seed crystal of the sulfate.

Jim
 
Members :

I've read your posts regard the problem making "alternate HNO3" and the
abnormal precipitate that is occurring, in some cases.

I am interested in trying this procedure and have been looking at NA or K
nitrates with locally obtained sulfuric drain cleaner.

My chemistry is from high school and my question may show it, but I find all
these cleaners contain multiple buffers. Would that seriously effect the results?

kafton
 
I wasn't happy with the drain cleaner that I was able to find, Virgin sulfuric and 12 buffers by the label. No strength was indicated. I got the same lemon slushy.

I had a better yield using boiled down battery acid and a solid salt by letting the vessel sit overnight and then placing the flask in salted ice. I saw no further salts form when I chilled the solution. I wish now I had measured the results.
 
If you are using the ntric to treat pins and e scrap stuff. I would just use the battery acid with added nitrate that's what I do, then if I need an AR type acid I just use the nitrate with muratic from lowes.
 
Hello all,

If you have a specialty hardware store ask for Klobber. 96% Sulfuric Acid. They sometimes keep it in the back room, they don't want the general public to use it. I had to tell them, what it was. About $14 a Qt. Be very careful using it!!! Danger Danger !! You will have to tell them your plumber recommended it, :oops: for your tough drain clog and you have been advised on how to use it safely by him. Read the directions on a regular strong bottle first so you know what you are talking about.
:wink:
 
G' Day all

I see a lot of TEMPS mentioned
what kind of thermometer should i get
have not seen any particular kind mentioned
if I know the kind I can get one I do interner research as a side
thanks all
great info here I have about 3 weeks into this research project
 
ALRIGHTEY THEN, I will look for those, might get both....thanks much guys
i ESTIMATE i am about 90 days from trying first refining effort
appreciate the help...
Don
 

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