Given an aqueous solution in which the [H+] = 2.5EE-7 M, what is the molar hydroxide ion concentration
To find the molar hydroxide ion concentration ([OH-]), we need to use the equation for the ion product of water (Kw) and the relationship between the hydrogen ion concentration ([H+]) and hydroxide ion concentration ([OH-]) in water.
The ion product of water is Kw = [H+][OH-] = 1.0 x 10^-14 at 25°C.
First, we can calculate the hydroxide ion concentration using the given hydrogen ion concentration. Since [H+][OH-] = Kw, we can rearrange the equation to solve for [OH-]:
[OH-] = Kw / [H+]
Substituting the given hydrogen ion concentration, we have:
[OH-] = (1.0 x 10^-14) / (2.5 x 10^-7)
Performing the calculation:
[OH-] = 4.0 x 10^-8 M
Therefore, the molar hydroxide ion concentration in the given aqueous solution is 4.0 x 10^-8 M.
To determine the molar hydroxide ion concentration ([OH-]) in an aqueous solution, you can use the equation for the autoionization of water:
H2O ⇌ H+ + OH-
In pure water, the concentration of both H+ and OH- ions is 1.0 x 10^-7 M at 25°C. However, in this case, the problem states that the [H+] is 2.5 x 10^-7 M, indicating that the solution is acidic.
In an acidic solution, the concentration of H+ is higher than that of OH-. Since the solution is not neutral, we need to calculate the OH- concentration using the equation:
[H+] × [OH-] = Kw
where Kw is the ion product constant of water, equal to 1.0 x 10^-14 M^2 at 25°C.
Rearranging the equation, we have:
[OH-] = Kw / [H+]
Substituting the values, we get:
[OH-] = 1.0 x 10^-14 M^2 / (2.5 x 10^-7 M)
Calculating this value, we find:
[OH-] ≈ 4.0 x 10^-8 M
Therefore, the molar hydroxide ion concentration in the given solution is approximately 4.0 x 10^-8 M.
(H^+)(OH^-) = Kw = 1E-14
You know Kw and (H^+), solve for (OH^-).