Consider a 9.5e-10 M solution of HClO4 at 283 K. What is the pH of the solution?
To find the pH of the solution, we first need to determine the concentration of H+ ions in the solution. HClO4 is a strong acid that dissociates completely in water, yielding H+ ions and ClO4- ions.
The given concentration of HClO4 is 9.5e-10 M. Since HClO4 is a strong acid, all of it will dissociate, resulting in the same concentration of H+ ions. Therefore, the concentration of H+ ions in the solution is also 9.5e-10 M.
The pH is defined as the negative logarithm (base 10) of the H+ ion concentration. So, we can use the equation:
pH = -log[H+]
Plugging in the concentration of H+ ions:
pH = -log(9.5e-10)
Calculating this in a scientific calculator or using a logarithm table, we find:
pH ≈ 9.02
Therefore, the pH of the solution is approximately 9.02.
First you must recognize that this is a very weak acid solution and that the H^+ contributed by the HClO4 is much less than the H^+ contributed by the H2O.
(H^+)(OH^-) = Kw
(H^+) = x from the H2O and 9.5E-10 from the HClO4.
(OH^-) = x
Kw you must look up (in your text) for Kw at 10 celsius. (283K-273 = 10 C).
Solve for x (H^+) and convert to pH.