sodium nitrate

one needs 1610 ml of nitric acid to dissolve one pound of copper---could someone tell me how much sodium nitrate is needed to do the same work??(how many grams or kilos)

Arthur,

According to :

Reagent Data

70% HNO3 has a density of ~1.42 g/cm3

Therefore :

1610 mL * 1.42 = 2286.2 grams

and @ 70% we have

0.7 * 2286.2 = 1600.34 grams of HNO3

or in terms of moles of HNO3 at ~63 grams per mole:

1600.34 / 63 = 25.4 Moles

Now for the NaNO3, we need 25.4 Moles at ~85 grams per mole or

25.4 * 85 = 2159 grams of NaNO3

The real question is can 1610 mL of 70% HNO3 dissolve 1 pound of copper? I believe GSP has posted the formulas for this before. The 1610 mL is one I calculated some time back and should be checked for accuracy as all information should be checked at least twice.

Wiki states the reaction of Copper and Nitric acid as :

3Cu + 8HNO3 → 3Cu(NO3)2 + 2NO + 4H2O

Cu is 63.55 grams per mole so the three moles above equals:

3 x 63.55 = 190.65 g

for one pound of copper we have

454 / 190.55 = 2.38 equivalents per pound as shown in the chemical equation above.

So for the 8HNO3's in the equation we need

2.38 * 8 = 19.04 Moles of HNO3 to dissolve 1 pound of copper.

70% HNO3 is 15.8 M so:

19.04 / 15.8 = 1.205 L or 1205 mL per pound of copper.

The error in my previous calculations was due to the fact that I used a different specific gravity for the HNO3. This density figure varies from chart to chart.

It would be very nice if a few other members would verify my figures and formulas for accuracy purposes and post their results.


Steve

thanks Steve, by analogy i did the following calculations: 3cu +8nano3=3cu(no3)2 + ------190.5grams of cu reacts with 680grams of nano3;so 454grams of cu is dissolved in 1619grams ---correct?

The simplest way to look at this is the ratio of NaNO3 to HNO3.


85 grams NaNO3 / 63 grams HNO3 = ~1.35

So whatever your molar mass of nitric acid needed just multiply 1.35 to get the mass of Sodium Nitrate needed. Be sure to correct for percentage concentration.

For example:

If 1 liter of 70% HNO3 weighs 1420 grams then the mass of HNO3 in the acid is :

0.7 x 1420 = 994 grams

Therefore there are 994 grams of HNO3 in 1 liter of 70% HNO3.

994 g x 1.35 = 1341.9 g of NaNO3

So ~1342 grams of NaNO3 contains the same mass of -NO3 that 1 Liter of 70% HNO3 does.

Steve

So, to answer Arthurs original question,

using 1.205 liters of 70 percent nitric to disolve one pound of copper,

and one liter of 70 containing 994 grams of nitic,

and that being equal to 1342 grams of sodium nitrate,

we would need 1.205 times 1342.
Or, 1617 grams of sodium nitrate to dislve 1 pound of copper.

But, with this type of nitric, wouldn't the sufuric come into play?
I mean sufuric acid will disolve copper, at least in it's oxide form....
Randy

randy,they are gold pins with copper underneath---not copper oxide

OK, but if you are using sulfuric........and sodium nitrate as the oxidizer...
it doesn't seem like it would take as much as the theoretical figure.
Well, I guess you will find out when you do this.

sodium nitrate and sulfuric acid would make nitric acid and sodium sulfate,
the concentration of sulfuric acid would determine the nitric acids strength, or percentage, then could figure for nitric acid, it could be caculated by that percentage, except for the NaSO4,also may have some sodium copper sulfate?

I can tell you, I use battery acid with potassium nitrate all the time. You will not need so much nitrate, and the fumes are way less.

I warm the sulfuric acid, about a cup full, and add a tablespoon of nitrate, stir to dissolve, then add my pins/foils ect. I do not add anymore nitrate unless the reaction stops, it is not needed. If the battery acid gets used up I add more, and small amount of nitrate.

The nitric acid attacks base metal forming coppernitrate, the sulfuric will subsistute making copper sulfate and more nitric this will go until the NO has all gased off which takes a while.

If there is lots of silver, I switch the ratios nitric solution and dose in the sulfuric.

Silver sulfate is filtered out.

Jim

I use 13.75-00-46 kno3 w/ new battery acid. I think, not sure here, that the only drawback using this instead of sodium nitrate is the amount the solution will hold of dissolved metal. I use it mostly for making silver nitrate so don't know if this even applies to the original question, but thought I'd put it in as (especially in Brazil) I would think saltpeter would be fairly easy to come by as a source for the oxidizer. It takes a bit more potassium nitrate than sodium nitrate to make the nitric but it work well for me.

Cheers,
John

thanks jamthee3,really we have saltpeter,but it comes from chile,it is more expensive then nano3

I see the above formula for the amount of Nitric acid to process copper. How would that equate out if you were using silver or sterling silver and not copper?

Just purchased my first bottle of Nitric Acid, 69.5%. $31.10 plus tax for a 7 puond bottle. Must remember to take it easy and see if I can rig up something to recover as much fumes as I can and reuse them. And we thought that gas was expensive...

A condenser is one of the best ways to keep as much acid as possible
Generally an acid kettle is used, other wise known as a reactor or reaction kettle.
It looks a bit like a funnel. there is an outlet on the bottom for draining.
On top a lid is compression fitted and based on your needs their are holes in the lid. They have common sizes 29/42, 24/40, etc. the centerone is for a motorized glass stir rod. sometime there are 4 additional surrounding it. a temp probe, fill/funnel, but on of them should be used for a condenser. it is a tall piece of jacketed glass. there are an inlet and an outlet. a small pump is hooked up to circulate water through it. I have found one of those 12v computer overclock setups work well. variable speed, pump, resevoir, radiator. the point is the cool water removes heat from your acid vapor though the walls of the glass, they never touch. the glass is curved or has glass wool packed in it to create areas for the vapor to condence. when condensed the acid drips back into the kettle body. You will get less vapor as well as make it last longer.
Just a heads up.
If you change the concentration of the nitric to 50% you will disolve 25%more copper as well as create less fumes
1000mls @ 68%HNO3-> 1360mls 50%
1L HNO3+ 360 mLs H20
its to early to make it equal 1 L but you get the idea.
It you are disolving Nickel alot of times copper is used to catalyse the reaction.