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    • Thread Starter

    I had a question asking, if the forwards reaction of the dissociation of an acid, HA, increased, what would happen to the pH.
    HA -> H+ + A-

    I understand the answer (decreases as the H+ ions increase), BUT why doesn't the A- have an impact?
    I understand that pH is a measure of H+ ions, but would there never be a point when they cancel out.. I swear my teacher did mention something about this.
    If anyone has an explanation for what I'm asking I would be grateful. Thank you!

    It's because pH depends only on free H+ concentration. You are probably aware that pH = -log[H+} and therefore A- isn't part of the calculation.

    The only effect A- concentration has would be to influence the position of equilibrium more to the right or left and hence change the H+ concentration. But A- concentration isn't directly part of pH measurement.
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