Hi
I am making a solutìon and need calcium chloride, but it is not available so I used calcium carbonate with HCL, as we know they will react with each other and give calcium chloride, water and carbon dioxide, will CaCL2 ionize in the solution to Ca+2 and Cl-2?
Or it will still as a white precipitate in the solution?
CaCl2 is highly soluble in aqueous solution, and it will stay in the ionized form in aqueous solution until about ~740 g/L weight concentration at room temperature 20 C. Since HCL is always stays in a diluted form, there will be plenty of water in such a system.....
If you have white solid it may be unreacted carbonate. Remember that CO2 is quite soluble in water and to finish the neutralisation you need to convert the bicarbonate to CO2 and expel the CO2 by boiling or purging with CO2-free gas.
HI,
I second the opinions of Prof. Alexander and Prof. Paul. We use such methods while we dont find the appropriate component while preparing culture media.
Hi Weaam Alali , if you used pure calcium carbonate and HCl as starting materials, you should end up with a clear solution of CaCl2 which is highly soluble in water. If you have impurities such as sulfate ion present, the reaction mixture could remain turbid due to the formation of CaSO4. In any case I would use a slight excess of CaCO3 in order to completely neutralize the HCl. You can then filter off any insoluble material and evaporate the clear filtrate to dryness to get your calcium chloride.
Weaam Alali, you're very welcome. Please let me know how it worked.
Eventually, precipitation may occur if the solution, somehow, becomes saturated in CaCO3. Carbonate speciation vs. pH diagram (Bjerrum plot) (*) suggests that for the acidic pH that in principle can be expected for not too dilute carbonated CaCl2 aq. solutions, CO2(aq) and (HCO3)- should largely predominate over CO32-. The last is expected to predominate over (HCO3)- for approx. pH > 10.4. Boiling should eliminate CO2(aq) but can also convert Ca(HCO3)2 to CaCO3 (likely to precipitate). You may consider to purge (stripping) the solution from dissolved CO2 by sparging N2. Note that the endpoint for the titration of a CaCO3 slurry with HCl (aq.) is not expected to be neutral, but acidic. For the purged solution is the pH of a CaCl2 aq. solution. Complete titration should clarify the former CaCO3 slurry.
(*) https://en.wikipedia.org/wiki/Carbonic_acid
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About predicting the pH of calcium chloride (CaCl2) aq. solutions ― cf. my posts at:
https://www.researchgate.net/post/How-to-increase-pH-for-a-solution-without-making-a-chemical-reaction-with-CaCl2
More about the pH of CaCl2 solutions: https://www.researchgate.net/post/Whats-the-best-choice-to-modify-the-PH-of-calcium-chloride-hexahydrate
https://www.researchgate.net/post/Why-is-my-anhydrous-calcium-chloride-not-going-into-solution