Final answer:
To find the hydrogen ion concentration [H+] given [OH−] = 0.0068 M, we use the ion-product constant for water to get [H+] = 1.47 x 10−9 M. Then, to calculate pH, we take the negative logarithm of [H+], resulting in a pH value of approximately 8.83.
Step-by-step explanation:
Calculating [H+] and pH from [OH−]
To find the concentration of hydrogen ions [H+] in a solution when the hydroxide ion concentration [OH−] is given, we use the ion-product constant for water (Kw) at 25°C, which is 1.0 x 10−14. The relationship is given by the formula Kw = [H+][OH−]. Therefore, to calculate [H+], we rearrange the equation to
[H+] = Kw / [OH−]. Plugging the values in, we get [H+] = 1.0 x 10−14 M / 0.0068 M, which calculates to approximately 1.47 x 10−9 M.
Next, to find the pH of the solution, we apply the formula pH = − log [H+]. Using our calculated [H+] value, pH = − log(1.47 x 10−9), which gives us a pH of approximately 8.83.