## Answer: Calculating the pH of an Acid Solution After Titration with NaOH

Titration is a laboratory technique used to determine the amount of a known reactive substance, or titrant, that is required to react with a given solution. In this case, the chemist is titrating 146.3 ml of a 0.2200M solution of benzoic acid with a 0.4100M solution of NaOH. The pKa of benzoic acid is 4.2. After adding 40.07 mL of the NaOH solution, the pH of the acid solution can be calculated using the following equation:

## Calculating the pH of the Acid Solution

The pH of an acid solution after titration with a base can be calculated using the following equation:
pH = pKa + log10(base/acid)

## Calculating the Ratio of Base to Acid

The ratio of base to acid can be calculated using the following equation:
base/acid = (Vbase / Vacid) x (Cbase / Cacid)
Where Vbase is the volume of base, Vacid is the volume of acid, Cbase is the concentration of base, and Cacid is the concentration of acid.

## Calculating the pH of the Acid Solution

Using the equation above, the ratio of base to acid can be calculated as follows:
base/acid = (40.07 mL / 146.3 mL) x (0.4100M / 0.2200M) = 0.2732

Using this value and the equation for calculating the pH of the acid solution after titration, the pH of the solution can be calculated as follows:
pH = 4.2 + log10(0.2732) = 3.42

Therefore, the pH of the acid solution after adding 40.07 mL of the NaOH solution is 3.42.

## Related Questions:

• What is titration?
• What is the equation for calculating the pH of an acid solution after titration with a base?
• What is the pKa of benzoic acid?
• How is the ratio of base to acid calculated?
• What is the volume of base used in the titration?
• What is the concentration of base used in the titration?
• What is the volume of acid used in the titration?
• What is the concentration of acid used in the titration?
• What is the pH of the acid solution after adding 40.07 mL of the NaOH solution?
• What is the molarity of the acid solution before titration?