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If the scale is 0-14, how come some acids and bases have pHs beyond the scale? Like how is it possible to get a negative pH or a pH above 14 if the scale is 0-14? Why don't we change the scale to accommodate those acids and bases?
Since pH is found by using the equation -log(x), where x is the concentration of hydrogen ions, pH will be negative as long as the hydrogen ions have a molarity greater than 1 (due to the behavior of the -log function). Because a negative pH is really hard to calculate experimentally due to lack of well-calibrated instruments, negative pHs are generally not mentioned. There has been some debate about whether the pH scale should be "open-ended" in the sense where arrows pointing to the left of 0 and to the right of 14 should be incorporated, but I think that for simplicity-related reasons, the 0-14 scale is most often used.
ZevMarx-Kahn3C wrote:Are there any examples we should know of that fall outside the 0-14 range?
I don't think there are any specific examples we should know, since I looked some up and they all look complicated. Just know that they are called superacids if the pH is negative (below 0).
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