| Pages:
1
2 |
Refinery
Hazard to Others
Posts: 371
Registered: 17-2-2014
Member Is Offline
Mood: Still
|
|
Apologies for my limited knowledge on chemical properties of acids, but I have a question regarding citric acid and sodium cyanide. Since sodium
cyanide is a base of weak acid and citric acid readily makes citrates from CaCO3, I am in impression that citric acid and sodium cyanide will cause
formation of hydrogen cyanide. Am I right, and what would be the balanced equation for this reaction?
Secondly I have heard that HCN may form polymers when liquefied/solidified. If I condense HCN fumes with salt ice bath, would it stay as pure liquid
that can be stored in suitable, pressure-rated glass container or would it eventually polymerize into room temperature solid? Is there any risk that
the possible polymer would act similar next to SO3 polymers that may decompose violently when heated?
|
|
|
Oscilllator
National Hazard
Posts: 659
Registered: 8-10-2012
Location: The aqueous layer
Member Is Offline
Mood: No Mood
|
|
Quote: Originally posted by woelen  | Do not get surprised about the difficulty you will have getting HCN out of the ferricyanide and HCl. The iron binds the cyanide ions very strongly and
even strong HCl does not simply release the HCN. You need to heat the liquid very strongly (boiling) and then you get impure HCN (mixed with HCl if
you use hydrochloric acid).
If you use 50% sulphuric acid or phosphoric acid, then you at least do not have contamination with acid vapor. But with these you also need to heat
strongly to drive off HCN and do not expect to have a good yield. Maybe you drive off 2 or so of the 6 cyanide ligands before total decomposition
occurs.
|
Woelen I feel you may have spoken to hastily. In the other enormous cyanide thread zan divine describes getting an 80% yield of cyanide, much more
that the 33% you suggested:
| Quote: Originally posted by Zan Divine | Typical run:
422 g (1 mol) K4[Fe(CN)6] added to 2 L round bottom with stir-bar. Add a solution of conc. H2SO4 (200 mL) in H2O (600 mL) in one portion. Attach
distillation head cooled with ice-water. Reaction appratus vented by tubing running out the window. Slowly heat the stirred blue suspension. You don't
need to go much above 50 - 60 degrees C. Foaming occurs in the first hour or longer as cyanide is distilled out and collected in an ice-cooled flask
containing 5 mL H2O and a couple mL H2SO4. Foaming subsides after a couple hours and then the suspension thickens. Adjust stirring as necessary. After
4 hours, 147 g HCN (80%) has been collected as a water-white liquid.
Dispose of residue in accordance with local laws.
|
|
|
|
| Pages:
1
2 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
