What mass in grams of potassium hydroxide is contained in 500 mL of solution that has a pH of 11.5?
Your response:
[OH] = 1.0 x 0^-14 / 11.5 This isn't correct. If the pH is 11.5, then the pOH = 14 - 11.5 = 2.5 = pOH and (OH^-) = 0.00316 M. It appears to me that you have Kw mixed up with pKw.
Sorry I don't quite understand can you please do a second step?
pH = 11.5
pH + pOH = 14, then
pOH = 14 - 11.5 = 2.5
If pOH = 2.5, then (OH^-) = 0.00316 M.
Certainly! Let's continue with the calculation.
To find the mass of potassium hydroxide (KOH) in grams, we need to know the molar concentration of potassium hydroxide in the solution.
The molar concentration of hydroxide ions ([OH^-]) can be calculated using the pOH value. We can convert the pOH value to the hydroxide ion concentration using the formula:
[OH^-] = 10^(-pOH)
In this case, the pOH is 2.5, so we can calculate:
[OH^-] = 10^(-2.5) = 0.00316 M
Now, we need to find the molar mass of potassium hydroxide (KOH), which is the sum of the atomic masses of its constituents: potassium (K), oxygen (O), and hydrogen (H).
K: 39.10 g/mol
O: 16.00 g/mol
H: 1.01 g/mol
Adding these masses together, we get:
39.10 g/mol + 16.00 g/mol + 1.01 g/mol = 56.11 g/mol
Finally, we can use the molar concentration of hydroxide ions and the volume of the solution to calculate the mass of potassium hydroxide.
mass = molar concentration x molar mass x volume
mass = 0.00316 M x 56.11 g/mol x 500 mL
First, let's convert the volume from milliliters (mL) to liters (L):
500 mL = 500/1000 = 0.5 L
Now, we can calculate the mass:
mass = 0.00316 M x 56.11 g/mol x 0.5 L = 0.0893 g
Therefore, the mass of potassium hydroxide (KOH) contained in 500 mL of the solution with a pH of 11.5 is approximately 0.0893 grams.