Soap Lake has actually a long background as a healing area. Indian tribes would certainly put aside their rivalries when they involved the lake to enjoy the high mineral content of the water. In the days prior to good antibiotics, hundreds of tourists would come and reap the soopoint waters of the lake. Soap Lake is alkaline, via water high quality though to be comparable to that of the moons of the earth Jupiter.

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The pOH Concept

Similar to the hydrogen-ion concentration, the concentration of the hydroxide ion can be expressed logarithmically by the pOH. The pOH of a solution is the negative logarithm of the hydroxide-ion concentration:

< extpOH = - extlog left< ceOH^- ight>>

The pH of a solution have the right to be related to the pOH. Consider a solution via a pH (= 4.0). The (left< ceH^+ ight>) of the solution would certainly be (1.0 imes 10^-4 : extM). Dividing (K_ extw) by this returns a (left< ceOH^- ight>) of (1.0 imes 10^-10 : extM). Finally the pOH of the solution equates to (- extlog left( 1.0 imes 10^-10 ight) = 10). This instance illustrates the following relationship.

< extpH + extpOH = 14>

The pOH range is equivalent to the pH range in that a pOH of 7 is indicative of a neutral solution. A basic solution has a pOH less than 7, while an acidic solution has a pOH of greater than 7. The pOH is convenient to use once finding the hydroxide ion concentration from a solution with a known pH.

Example (PageIndex1)

Find the hydroxide concentration of a solution via a pH of 4.42.


Step 1: List the well-known values and plan the trouble.


pH (= 4.42) pH (+) pOH (= 14)


(left< ceOH^- ight> = ? : extM)

First, the pOH is calculated, adhered to by the (left< ceOH^- ight>).

Tip 2: Solve.

<eginalign extpOH &= 14 - extpH = 14 - 4.42 = 9.58 \ left< ceOH^- ight> &= 10^- extpOH = 10^-9.58 = 2.6 imes 10^-10 : extM endalign>

Tip 3: Think about your result.

The pH is that of an acidic solution, and also the resulting hydroxide-ion concentration is less than (1 imes 10^-7 : extM). The answer has 2 considerable numbers because the offered pH has 2 decimal areas.

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The diagram listed below mirrors all of the interrelationships in between (left< ceH^+ ight>), (left< ceOH^- ight>), pH, and also pOH.

what is the [oh-] in a solution that has a ph of 12.80?