TmNhRhMgBrSe
Hazard to Others
Posts: 112
Registered: 4-7-2019
Member Is Offline
|
|
Purify calcium nitrate
I make calcium nitrate but solution is yellow. How to remove yellow colour?
|
|
|
B(a)P
International Hazard
Posts: 1139
Registered: 29-9-2019
Member Is Offline
Mood: Festive
|
|
You need to provide more detail.
Do you know or suspect what the impurity is?
How did you make the calcium nitrate?
What were your starting products?
What do you want to do with it, the impurity may not be a problem depending on your intended use.
Any photos?
|
|
|
TmNhRhMgBrSe
Hazard to Others
Posts: 112
Registered: 4-7-2019
Member Is Offline
|
|
CaCO3 is from food's gas absorber.
I heat CaCO3 to remove any organic compound.
Add CaCO3 to HNO3, filter, add few drops solution to NaSCN, solution become red, add some NaOH to calcium nitrate, some white precipitate appear,
filter, solution and solid also are yellow, add few drops solution to NaSCN, solution didn't change colour.
I want to make Ca(NO3)2 crystals.
I now don't have photos. Maybe later.
sorry for bad english
|
|
|
B(a)P
International Hazard
Posts: 1139
Registered: 29-9-2019
Member Is Offline
Mood: Festive
|
|
Was the CaCO3 and HNO3 in stoichiometric amounts?
Why add NaSCN or NaOH?
Why not just add CaCO3 in excess to HNO3, then filter.
You would then have a Ca(NO3)2 solution.
|
|
|
TmNhRhMgBrSe
Hazard to Others
Posts: 112
Registered: 4-7-2019
Member Is Offline
|
|
I don't know how to find HNO3 concentration so didn't measure how much.
I didn't add NaSCN. The NaSCN is in another test tube. I add few drops Ca(NO3)2 solution to NaSCN. I add NaOH to remove iron.
sorry for bad english
|
|
|
Sulaiman
International Hazard
Posts: 3695
Registered: 8-2-2015
Location: 3rd rock from the sun
Member Is Offline
|
|
I think that this could be a good opportunity to practice purification by recrystalisation 
Grow your crystals, harvest them, dissolve in distilled water and recrystalise, repeat as necessary.
start with a lot of calcium nitrate as at each recrystalisation step you need to collect only a portion of the total,
recrystalise SLOWLY to get reasonably large crystals
and do not try to crystalise out all at each step.
I have not tried myself, but activated cabon may decolourise the solution(s)
CAUTION : Hobby Chemist, not Professional or even Amateur
|
|
|
RogueRose
International Hazard
Posts: 1593
Registered: 16-6-2014
Member Is Offline
|
|
Quote: Originally posted by Sulaiman  | I think that this could be a good opportunity to practice purification by recrystalisation
Grow your crystals, harvest them, dissolve in distilled water and recrystalise, repeat as necessary.
start with a lot of calcium nitrate as at each recrystalisation step you need to collect only a portion of the total,
recrystalise SLOWLY to get reasonably large crystals
and do not try to crystalise out all at each step.
I have not tried myself, but activated cabon may decolourise the solution(s) |
I highly recommend a little activated carbon to see if it doesn't clear things up.
Also i think Ca(NO3)2 dissolves pretty well in methanol so maybe that could be a way to purify it if the other compounds don't dissolve well in
methanol.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
