Most Important Selected Qs for JEE AdvancedChemistryIonic Equilibrium
A buffer solution contains 0.2 mole of acetic acid and 0.25 mole of potassium acetate per litre. Calculate the change of pH of the solution if 0.5 ml of 1 M HCl is added to it. The pK _ a of CH ₃ COOH is 4.76. The volume change on the addition of HCl may be neglected.
Correct answer
0.002
Step-by-step solution
pH of the solution before adding HCl pH = pK _ a + 0.25 0.20 =4.8569 HCl added =0.0005 mole After adding HCl aligned [ CH ₃ COOH ] & =0.20+0.0005=0.2005 [ CH ₃ COOK ] & =0.25-0.0005=0.2495 aligned pH =4.76+ 0.2495 0.2005 =4.8549 Change in pH =4.8569-4.8549=0.002