Question

Suppose 10.00 mL of 0.200 M HCl is added to an acetate buffer prepared by dissolving 0.100 mol of acetic acid and 0.110 mol of sodium acetate in 0.100 L of solution. What are the initial and final pH values? What would be the pH if the same amount of HCl solution were added to 125 mL of pure water? Initial pH = Final pH =

Answer 1

For initial pH we use Henderson–Hasselbalch equation as there is buffer solution.After addition of HCL , we calculate number of moles of HCL added to buffer solution. As we know that acid HCL react only with salt and form acetic acid and NaCl . Then calculating required moles of HCL is require or consume to complete the reaction we final end with again salt acetate and acetic acid but different concentrations and again using Henderson equation and calculate pH.

For second part we know that pH of pure water is 7 at room temperature. But after additon of HCL solution pH changes. As you in below image solution.