A solution of NaOH with pH 13.68 requires 35.00 mL of 0.128 M HClO_4_ to reach the equivalence point. What is the volume of the NaOH solution?
Convert pH 13.68 to OH^- (which will be in moles/L or M), then
mL NaOH x M NaOH = mL HClO4 x M HClO4.
How do I do convert the pH to the OH?
Answered above.
To find the volume of the NaOH solution, we need to use the equation that relates the amount of acid (HClO4) to the amount of base (NaOH) at the equivalence point. The equation is:
M1V1 = M2V2
Where:
M1 is the concentration of the acid (HClO4) = 0.128 M
V1 is the volume of the acid = 35.00 mL = 35.00 mL / 1000 = 0.03500 L
M2 is the concentration of the base (NaOH) (which we need to find)
V2 is the volume of the base (NaOH) solution (which we need to find)
First, let's convert the pH of the NaOH solution to its concentration (M).
The pH of 13.68 tells us the concentration of hydroxide ions ([OH-]) in the solution. The formula to calculate the concentration (M) from pH is:
[OH-] = 10^(-pOH)
pOH = 14 - pH
pOH = 14 - 13.68
pOH = 0.32
Therefore, [OH-] = 10^(-0.32) = 0.50119 M
Since NaOH is a strong base, it completely dissociates into Na+ and OH- ions in water. So the concentration of NaOH is the same as the concentration of hydroxide ions.
M2V2 = M1V1
(0.50119 M)(V2) = (0.128 M)(0.03500 L)
Now, solve for V2:
V2 = (0.128 M)(0.03500 L) / 0.50119 M
V2 = 0.008934 L = 8.934 mL
Therefore, the volume of the NaOH solution is 8.934 mL.