Question

What is a worked example for the calculation of PH at the equivalent point of formic acid with sodium hydroide?

Answer 1

To calculate the pH at the equivalent point of formic acid (HCOOH) with sodium hydroxide (NaOH), we need to determine the number of moles of acid and base at the equivalence point and then use that information to calculate the pH.

Let's assume we have a solution of formic acid with a known concentration and volume, and we titrate it with a sodium hydroxide solution of known concentration until the equivalence point is reached.

1. Determine the balanced chemical equation for the reaction between formic acid and sodium hydroxide: HCOOH + NaOH -> HCOONa + H2O

2. Determine the stoichiometry of the reaction: From the balanced equation, we can see that one mole of formic acid reacts with one mole of sodium hydroxide.

3. Calculate the number of moles of formic acid: Moles of formic acid = concentration of formic acid (in mol/L) × volume of formic acid solution (in L)

4. Calculate the number of moles of sodium hydroxide: Since the stoichiometry is 1:1, the moles of sodium hydroxide will be equal to the moles of formic acid.

5. Determine the volume of sodium hydroxide required to reach the equivalence point: Volume of sodium hydroxide solution (in L) = Moles of sodium hydroxide / concentration of sodium hydroxide (in mol/L)

6. Calculate the concentration of formic acid remaining at the equivalence point: The moles of formic acid initially present minus the moles of sodium hydroxide used will give the moles of formic acid remaining. Moles of formic acid remaining = Moles of formic acid initially - Moles of sodium hydroxide used Concentration of formic acid at the equivalence point = Moles of formic acid remaining / Volume of formic acid solution (in L)

7. Calculate the pOH at the equivalence point: pOH = -log10(concentration of hydroxide ions at the equivalence point)

8. Calculate the pH at the equivalence point: pH = 14 - pOH

By following these steps, you can determine the pH at the equivalent point of formic acid with sodium hydroxide. Remember to use the appropriate values for the concentrations and volumes involved in your specific experimental setup.