Calculate the volume at which pH = pKa if 30.00mL of weak acid with a concentration of 0.0955M is titrated
against a strong base with a concentration of 0.1233M.
.0955molacid*.030L weak acid= .002865 mol acid/.1233 mol base= .02325 L base/2=11.62mL
I got confused once I found my moles of acid, did I finish it correctly?
You are right on the money!
Why did you divide your L by 2?
To calculate the volume at which pH = pKa, we need to follow these steps:
Step 1: Identify the weak acid and the strong base involved in the titration.
In this case, we have a weak acid being titrated against a strong base.
Step 2: Write the balanced chemical equation for the reaction.
Let's assume the weak acid is HA and the strong base is BOH.
The balanced equation for their reaction would be:
HA + BOH → BA (salt) + H2O
Step 3: Determine the dissociation constant (Ka) of the weak acid.
The dissociation constant (Ka) gives us the acidity of the weak acid. It is related to the pKa value, which is the negative logarithm of Ka.
If we have the pKa value, we can calculate Ka using the equation:
Ka = 10^(-pKa)
Step 4: Calculate the initial moles of weak acid in the solution.
Given the volume and concentration of the weak acid, we can calculate the initial moles using the equation:
moles of weak acid = volume (in liters) * concentration
Step 5: Calculate the moles of strong base required for neutralization.
Since we know the balanced chemical equation, we can determine the stoichiometry between the weak acid and the strong base. The moles of weak acid will be equal to the moles of strong base required for neutralization.
Step 6: Calculate the volume of strong base required.
Using the moles of strong base and its concentration, we can calculate the volume (in liters) of the strong base required using the equation:
volume of strong base = moles of strong base / concentration
Step 7: Convert the volume of the strong base to milliliters (mL).
Multiply the volume in liters by 1000 to get the volume in milliliters.
By following these steps, you should be able to calculate the volume at which pH = pKa for the given titration.