If the hydroxide ion concentration in a lake is 10‐10 M what is the lake’s pH?
To determine the pH of a solution, you need to know the concentration of hydrogen ions (H+). However, in this question, we are given the concentration of hydroxide ions (OH-).
In a neutral solution, the concentration of H+ ions is equal to the concentration of OH- ions. This means that for every hydroxide ion, there is one hydrogen ion.
Using this knowledge, we can calculate the concentration of hydrogen ions (H+) using the equation [H+] × [OH-] = 1.
Given that the concentration of hydroxide ion is 10^(-10) M, we can substitute this value into the equation:
[H+] × 10^(-10) = 1
Rearranging the equation to solve for [H+], we have:
[H+] = 1 / 10^(-10)
[H+] = 10^10
Now that we have the concentration of hydrogen ions, we can find the pH using the equation:
pH = -log[H+]
Substituting the value of [H+], we get:
pH = -log(10^10)
Using the logarithmic property log(a^b) = b * log(a), we have:
pH = 10 * (-log(10))
The logarithm of base 10 for 10 is 1, so:
pH = 10 * (-1)
pH = -10
Hence, the pH of the lake, given the hydroxide ion concentration of 10^(-10) M, is -10.
It's important to note that a negative pH value is not within the traditional pH scale of 0-14, which indicates the acidity or alkalinity of a solution. This suggests that the lake might be highly basic or caustic.