If you add Alum - $\ce{Al2(SO4)3}$, to a clay water sample which contains $\ce{Ca(HCO3)2}$ - due to the water's alkalinity, the pH of this water sample would drop as Alum drops the pH levels. How would you counteract this imbalance. As in, what could you add to the sample to keep the pH the same as it was before the addition of Alum.

  • $\begingroup$ If you've lost your original browser cookie, you can use the Contact Us link at the bottom to recoup your account. Then you can edit your post without having to leave an answer. $\endgroup$
    – jonsca
    Apr 26 '15 at 6:15
  • 2
    $\begingroup$ Just to make sure: aluminium sulfate - Al2(SO4)3 is not considered as "Alum". Alums are double sulfate salts, like KAl(SO4)2. $\endgroup$
    – AstronAUT
    Sep 23 '15 at 19:16

One thing I can suggest are buffers which maintain the pH of a solution within a certain limit when either acid or bases are added. These often are based around the concept of weak acids or bases. See this.


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