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Re: [APD] KH question
Liz, I am relieved to learn that I am still not a chemist! For a
moment I was afraid I was one.
On Nov 19, 2006, at 9:46 PM, Liz Wilhite wrote:
> I know I should let this pass but...
> Adding carbonate does buffer the system. A buffer solution contains
> a weak
> acid and its conjugate base. Carbonate is a base which reacts with
> water, an
> amphoteric substance, forming bicarbonate ions and clusters of water
> molecules of various numbers and shapes that have hydrogen ions
> with them. The conjugate base of bicarbonate is carbonate. If you add
> bicarbonate to water, it also reacts with water forming carbonate
> ions and
> those same clusters of water molecules with hydrogen ions.
> Adding CO2 to water forms "carbonic acid" which is either an
> strong acid or a pretty weak acid, depending upon how you define
> acid." The dissolution of CO2 in water yields a solution
> containing water
> molecules associated with hydrogen ions, bicarbonate and carbonate
> The addition of carbonate (or bicarbonate) ions to water creates a
> to which an acid can be added without a large change of pH -- i.e. it
> creates a buffer solution.
> I was just looking to know if anyone with a relatively low KH had
> suffered a
> pH crash as a KH of 3 indicates a reasonably low concentration of
> and bicarbonate ions in solution, even assuming that there are no
> other ions
> interfering with the KH test and I'm not certain that is a valid
> assumption. I appreciate knowing that you haven't had any troubles
> so I
> shouldn't expect any, either.
> On 11/19/06, Vaughn Hopkins <hoppycalif at yahoo_com> wrote:
>> Where I live now my tap water has KH below 1. I don't add anything
>> to "buffer" it. I use 40 ppm of CO2 in the tank, and the pH hasn't
>> changed enough to cause either the fish, shrimp or plants to
>> Incidentally, to buffer a solution requires adding a substance that
>> resists increases in pH and a substance that resists decreases in pH
>> - always two substances. Adding just one, like bicarbonates, only
>> shifts the pH higher, it does not buffer the solution to a
>> specific pH.
>> I just felt a need to be pedantic there. Sorry.
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