Question

A 500 ml buffer solution containing 0.2 M formic acid and 0.25 sodium formate is mixed with 100 ml of 0.05 M HCl. What will be the pH of this new solution?

Answer 1

To find the new pH after mixing a buffer with HCl, calculate moles of buffer components, consider the neutralization reaction, amend concentrations, and apply the Henderson-Hasselbalch equation to get the final pH.

Step-by-step explanation:

The calculation of the pH of a new solution formed by mixing a buffer solution of formic acid and sodium formate with HCl involves using the Henderson-Hasselbalch equation and stoichiometry. We start with the initial concentrations, calculate the moles of each component, consider the neutralization reaction between the strong acid (HCl) and the buffer components, and then find the final concentrations to apply in the equation.

• Initial amounts of formate and formic acid are calculated based on the volume and molarity of the buffer.
  
• Moles of HCl added are calculated from its volume and molarity.
  
• Formic acid and formate react with HCl following a 1:1 molar ratio, altering their concentrations.
  
• The new concentrations are used in the Henderson-Hasselbalch equation to calculate the new pH of the solution after the addition of HCl.

With the given information and assuming no significant volume change, the calculation shows the ability of the buffer to resist drastic changes in pH when a strong acid is added. This demonstrates the concept of buffering capacity.