Home Cosmetic Science Talk Formulating General Science making solutions

  • making solutions

    Posted by belassi on July 6, 2017 at 4:57 pm

    Making solutions sometimes causes me problems.
    For instance, adding citric acid and sodium benzoate to water. Which should be dissolved first? And when you have several different ingedients? I had a problem last week when I made a citric acid solution and then tried to add sodium benzoate, the benzoate refused to dissolve and floated around on top like some insoluble substance.
    I wish there were some kind of chart that shows the order in which to put things in solution.

    drbobverdient-biz replied 6 years, 8 months ago 4 Members · 8 Replies
  • 8 Replies
  • drbobverdient-biz

    Member
    July 6, 2017 at 10:22 pm

    It is a matter of chemistry CA first makes solution acid in which sodium benzoate as benzoic acid is insoluble.

  • belassi

    Member
    July 6, 2017 at 11:20 pm

    So you’re suggesting it will be more successful to dissolve the benzoate first? Or to make a separate solution for each ingredient and mix them all together?

  • bill_toge

    Member
    July 6, 2017 at 11:25 pm

    in this case separate solutions would be the better option: even if you dissolve the sodium benzoate first, it’ll precipitate and eventually crystallise out

  • belassi

    Member
    July 6, 2017 at 11:33 pm

    Aha. I guess this implies … something I recall about ionic charge values or valence electrons or whatever. Hmm. More phases.

  • drbobverdient-biz

    Member
    July 6, 2017 at 11:34 pm

    You can add the SB at the end of the process after you adjust PH with CA.

  • belassi

    Member
    July 6, 2017 at 11:36 pm

    OK thanks. 

  • doreen

    Member
    July 8, 2017 at 12:58 pm

    @DRBOB@VERDIENT.BIZ
    You can add the SB at the end of the process after you adjust PH with CA.

    This is also how I do it with potassium sorbate, I expected precipitation problems with it because of its formation to sorbic acid in the acidic CA environment, as the sorbic acid also is only slightly water soluble.

  • drbobverdient-biz

    Member
    July 8, 2017 at 2:50 pm

    Doreen81 You are right as it seems like this is the best way to handle these types of preservatives:also they remain very stable and functional with time.

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