A certain weak base has a Kb of 9.00 × 10-7. What concentration of this base will produce a pH of 10.34?
pH + pOH = pKw = 14.
You know pH and pKw, solve for pOH, then
pOH = -log(OH^-) and solve for (OH^-).
..........BH + HOH ==> BH2^+ + OH^-
Kb = (BH2^+)(OH^-)/(BH)
You know (OH^-) = (BH2^+) and Kb, solve for (BH) = concn of base.
To determine the concentration of a weak base that produces a specific pH, we need to use the relationship between the pH and the pOH of a solution.
pOH is calculated as the negative logarithm (base 10) of the hydroxide ion concentration ([OH-]). Since we're given the pH, we can find the pOH using the following equation:
pOH = 14 - pH
In this case, the pH is 10.34, so we can calculate the pOH:
pOH = 14 - 10.34
pOH = 3.66
Now, we can convert the pOH to the hydroxide ion concentration ([OH-]) using the following equation:
[OH-] = 10^(-pOH)
[OH-] = 10^(-3.66)
[OH-] = 0.00297 M
The concentration of the weak base will be equal to the concentration of the hydroxide ions since it dissociates to form OH- ions in water. Therefore, the concentration of this weak base that produces a pH of 10.34 is 0.00297 M.