Gargamel - 13-8-2013 at 07:28
Hi guys,
well i've got to vessels of copper nitrate and the look like this:
-the first is completely covered by liquid.
-the second is a wet cake, mushy, dripping wet.
Well, first thing is, how do I calculate with this stuff?
Both are supposed to be trihydrate, but this isn't true anymore of course 
Drying copper nitrate by heating is impossible without decomposition. Now how do I bring this stuff to a hydrate form from where I can say that much
gramms equals so much gramms Coper nitrate and so much water?
Since there is still solid stuff in there - can I assume this to be the highest hydrate - hexahydrate?
Second thing - shelf life. Is copper nitrate stable in solution?
The stuff is not very fresh.
Also Wikipedia gives a melting point for the hexahydrate of only 26°C above which it is supposed to decompose. Other sources say the "the hydrates
form basic copper nitrate at 80°C and copper oxide above 170°C".
Summer here was very hot in the last weeks and temperature at my storage place was higher on some days.
[Edited on 13-8-2013 by Gargamel]
Magpie - 13-8-2013 at 10:15
I made some copper nitrate once. I tried to dry it but couldn't due to its strong deliquesence. So I kept it as an aqueous solution. But I also
needed to know exactly the strength of this solution. So I used a wet chemistry quantitative analysis procedure for copper. This worked well.
Hexavalent - 13-8-2013 at 10:52
Would this be titrating against EDTA, or the sodium salt?
Dany - 13-8-2013 at 10:59
Hello Gargamel
I suggest you to perform a redox reaction between a given weight of your hydrated copper nitrate and excess reducing metal (e.g.,zinc). Zinc plate can
be removed from AA batteries and cleaned. with excess zinc in solution, the copper will be reduced to solid copper and zinc oxidized to zinc ion. you
can either weight the zinc plate before and after the reaction or weighting the copper that has been precipitate in the solution. from balancing the
simple equation you can estimate approximately the quantity of copper nitrate. but unless you have an analytical balance the method is only a rough
one for this kind of analysis.
Another method is to react a certain weight of your copper nitrate compound with excess citric acid in alkaline solution so as to obtain a deep blue
citrate-copper solution. this solution can serve as an oxidizing reagent to test reducing sugar like glucose. when you heat the citrate-copper
solution with excess glucose a solid red-brick of Cu2O precipitate. you can also weight the Cu2O precipitate to estimate the quantity of copper
initially used.
Dany
Magpie - 13-8-2013 at 11:40
For Hexavalent: iodometry. I standardized my reagents using bits of copper wire.
[Edited on 13-8-2013 by Magpie]
bfesser - 13-8-2013 at 11:54
The <strong><a href="viewthread.php?tid=25537">Reduction of Copper (II) Compounds</a></strong> thread has some useful info and
links.