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Author: Subject: Nitric acid
Biochemicus Energeticus

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[*] posted on 1-1-2006 at 17:49

See one of my posts above, it gives the density versus concentration of nitric acid.

You take a defined volume, i.e. 50 ml and then weigh it. The closer the the weight is 75.1 g, the closer you are to 100 %.

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lab constructor

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[*] posted on 1-1-2006 at 19:03

Your picture showed (I believe) a thermometer in a 2-hole rubber stopper at the top of your condenser. Although your equipment is not the best this is the right idea for placement of the thermometer. You want it in the vapor space just at the entrance of the condenser. You should see a drop of condensate on the thermometer bulb all through the distillation.

Someone has posted a link to a vapor-liquid equilibrium diagram for the HNO3-water system in an earlier post, this thread. This is your roadmap to what is happening during the distillation. IIRC the boiling point of pure HNO3 is around 80C, that for the 68% azeotrope around 120C, and of course, for water is 100C. The temperature you read will tell you where you are in concentration of condensate by reading the vapor curve. The liquid curve shows what's in the pot. So read across at the temperature you are at and you get both concentrations: pot and vapor (or condensate).

If you are initially rich in water you will be on one side of the azeotrope. If initially lean in water you will be on the other side of the azeotrope. If you have a simple column (1 stage), as you do, your temperature will be changing until you reach the azeotrope in the pot.

Note: the terms "rich" and "lean" refer to the azeotropic concentration, i.e., 68% HNO3.

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[*] posted on 3-1-2006 at 19:22

OK, this is my first post here. I was looking for a source of nitric acid in order to silver my telescopes mirrors. After looking through this I thought about something, but I'm not sure if it would work.

2 H2O2 + NH4OH --> 2 H20 + HNO3 + 2 H2

So how much of a problem do I have there?
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International Hazard

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[*] posted on 3-1-2006 at 20:13

The ammonium ion is too stable to be oxidized by aqueous hydrogen peroxide. This has been discussed around here somewhere, I don't remember where exactly.
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International Hazard

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[*] posted on 4-1-2006 at 09:19

Jasso, under the right conditions that would oxidize to hydrazine:

H2O2 + 2 NH4OH --> N2H4 + 4 H2O

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Hazard to Others

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[*] posted on 10-10-2006 at 01:40

Hi, Ive had the same problem.
I used a glass distilation apparatus without such thin tubes, all the tubes were very thick and specially made for distilation, also no rubber corkes were used, only glass. The condenser was a coil condenser with ice cold water pumped around it.
After 5 hours of heating to 90 degrees very small amount of yellow colored liquid started to appear in the coil.
in the end of the process(about 12 hours and when my burner died :( ) i finished with about 30ml of yellow fuming liquid with 1.44 density :(. quite dissapointing.
could anyone please advise me what to do?
maybe i should use a linear condenser?
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