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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: Aymeric on December 05, 2020, 02:19:56 PM

Title: Saturating a solution with sodium bicarbonate
Post by: Aymeric on December 05, 2020, 02:19:56 PM
Hello,

I’m not sure where this question best fits, sorry if this is the wrong sub-forum.

I’m a complete amateur and have very basic knowledge of chemistry. I would like to saturate a liquid solution consisting of almost only water, with sodium bicarbonate.
I have no idea how to go about calculating the maximum amount of sodium bicarbonate I can dissolve into this solution to saturation, without having too much residue clumping up at the bottom.

Thanks for your guidance!

PS. This is not homework, just a personal project.
Title: Re: Saturating a solution with sodium bicarbonate
Post by: Corribus on December 05, 2020, 03:41:48 PM
You can look up the solubility of sodium bicarbonate, although that relies on assumption of standardized conditions.  Better to just dissolve until saturation and then filter.
Title: Re: Saturating a solution with sodium bicarbonate
Post by: Aymeric on December 06, 2020, 07:47:25 AM
Thank you Corribus. I’ve tried adding a little less than the solubility (87 g/L, so I added 8g to a 100 mL solution), I mixed for several minutes at high speed, and a few hours later about half of the bicarbonate sodium is clumped up at the bottom of my vial  :'(
Title: Re: Saturating a solution with sodium bicarbonate
Post by: AWK on December 06, 2020, 08:31:28 AM
It is not known why you need a saturated solution of NaHCO3. But to obtain such a solution is quite a challenge. Typically, solutions are simply heated to speed up dissolution. In the case of sodium bicarbonate, this method is useless because already at 40°C the compound begins to slowly decompose thermally and around 80 degrees the decomposition is very fast. In addition, NaHCO3 dissolves extremely slowly in water. The chemist should be patient. A week of intense mixing will probably be enough.
Title: Re: Saturating a solution with sodium bicarbonate
Post by: Aymeric on December 06, 2020, 08:46:48 AM
Quote from: AWK on December 06, 2020, 08:31:28 AM
It is not known why you need a saturated solution of NaHCO3. But to obtain such a solution is quite a challenge. Typically, solutions are simply heated to speed up dissolution. In the case of sodium bicarbonate, this method is useless because already at 40°C the compound begins to slowly decompose thermally and around 80 degrees the decomposition is very fast. In addition, NaHCO3 dissolves extremely slowly in water. The chemist should be patient. A week of intense mixing will probably be enough.
Thank you for the pointers! I’ll just be patient then :)