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"Sodium alginate solution" vs. "Alginic acid"

  1. Jun 17, 2017 #1
    Hi everyone.
    I'm doing research with sodium alginate (NaC6H7O6) and I really need your help.

    Sodium alginate is a cell wall component of seaweed or brown algae.
    During the research, I read some pages telling that we can get alginic acid by dissolve sodium alginate in water.

    But what I think is that, if the NaC6H7O6 is dissolve in water, it will ionized and loss Na+.
    Then the solution will be a base, not an acid....
    And I test the pH with sodium alginate solution and I got a pH 7
    (Actually, I didn't dissolve much powder)

    Is it right that the solution of sodium alginate is a really acid???
  2. jcsd
  3. Jun 17, 2017 #2


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    Staff: Mentor

    How did you test for pH?

    NaC6H7O6 is an experimental formula, not the real one (not that it matters much, just for clarification), as the alginic acid is a natural polymer.

    Solution of alginate should have pH a bit on the basic side, typical for solutions of salts of weak acids. No idea what water you have used for dissolving and what is the concentration, so it is a bit difficult to comment on, but in general DI water is typically a bit acidic due to the dissolved CO2, if the pH of the solution is 7 chances are it is already more alkaline than it was before.
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