Question

How do you determine pH at an equivalence point?

Answer 1

Hint: A point in a titration at which the amount of acid added through the burette is sufficient to neutralize completely the base solution which is present in the conical flask is called equivalence point.

Complete step by step answer:
- In the question it is asked how we can determine pH at an equivalence point.
- At equivalence point the concentration of the acid and base will be zero and there will only salt and water.
- We can call the equivalence point a neutralization point also.
- There is a formula to calculate the equivalence point when a weak acid is going to react with a strong base and it is as follows.
\[{{K}_{b}}=\dfrac{[O{{H}^{-}}][HA]}{[{{A}^{-}}]}\]
 - From the above formula after substituting the known values we will get the concentration of the base.
- Now substitute the base concentration in the below formula to get the pOH of the solution.
pOH = - log (base concentration)
- After knowing the pOH of the solution we can calculate the pH of the solution by using the below formula.
pH + pOH = 14
pH = 14 – pOH.
- This is how we can calculate the pH of the solution at equivalence point.

Note: pH is the negative logarithm of the hydrogen ion concentration present in the solution. pH of the solution will give the information about the acidity of the given solution. By using pH we can find the acidity or basicity of the solution.