Most Important Selected Qs for JEE AdvancedChemistryIonic Equilibrium
Paragraph: Buffer is a solution whose pH does not change significantly on addition of a small amount of acid or alkali or on dilution. Answer the following questions: Question: The ratio of pH (approximately) of solution (I) containing 1 mole of CH ₃ COONa and 1 mole of HCl and solution (II) containing 1 mole of CH ₃ COONa and 1 mole of acetic acid in one litre is :
Options
- A1: 2
- B2: 1
- C1: 3
- D3: 1
Correct answer
A. 1: 2
Step-by-step solution
[ CH ₃ COOH ]= No. of moles Volume of solution = 1 1 =1 [ H ⁺ ]= C = C K _ a C = K _ a C = K _ a i.e. pH ₁=- 1 2 K _ a = 1 2 pK _ a Solution (II) 1 CH ₃ COONa + 1 CH ₃ COOH It is buffer. pH ₂= pK _ a + [ CH ₃ COONa CH ₃ COOH ] aligned & pH ₂= pK _ a + 1 1 & pH ₂= pK _ a & pH ₁ pH ₂ = 1 2 aligned