A weak acid mathrmHA has degree of dissociation x. Which option gives the correct expression of mathrmpH - mathrmpK_mathrma ?

Solution & Explanation

### Related Formula For a weak acid solution: mathrmHA rightleftharpoons mathrmH^+ + mathrmA^- K_a = frac[mathrmH^+][mathrmA^-][mathrmHA] ### Step 1: Expressing Concentration Let the initial concentration be a. At equilibrium: [mathrmHA] = a(1-x), quad [mathrmH^+] = ax, quad [mathrmA^-] = ax Substituting into the equilibrium expression: K_a = frac(ax)(x)1-x = [mathrmH^+] left(fracx1-xright) ### Step 2: Logarithmic Rearrangement Taking negative logarithms on both sides: -log K_a = -log [mathrmH^+] - logleft(fracx1-xright) mathrmpK_a = mathrmpH - logleft(fracx1-xright) mathrmpH - mathrmpK_a = logleft(fracx1-xright) ### Pattern Recognition Sees: mathrmpH - mathrmpK_a for weak acid equilibrium. Shortcut: This is equivalent to the Henderson-Hasselbalch framework: mathrmpH = mathrmpK_a + logfrac[textSalt][textAcid] = mathrmpK_a + logfracx1-x. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Chemistry: Ionic Equilibrium

Reference Study Guides

Ionic Equilibrium

More Ionic Equilibrium Previous-Year Questions — Page 6

Q62 jee_main_2024_31_jan_morning Equilibrium Constant
For the given reaction, choose the correct expression of K_C from the following :- Fe_(aq)^3+ + SCN_(aq)^- rightleftharpoons (FeSCN)_(aq)^2+
  • A. K_C = frac[FeSCN^2+][Fe^3+][SCN^-]
  • B. K_C = frac[Fe^3+][SCN^-][FeSCN^2+]
  • C. K_C = frac[FeSCN^2+][Fe^3+]^2[SCN^-]^2
  • D. K_C = frac[FeSCN^2+]^2[Fe^3+][SCN^-]

Solution

### Related Formula K_C = frac[textProducts][textReactants] ### Core Logic K_C = fractextProducts ion conc.textReactants ion conc. K_C = frac[FeSCN^2+][Fe^3+][SCN^-] ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Chemistry: Equilibrium

More Ionic Equilibrium Questions — jee_main_2025_28_jan_morning

Practice all Ionic Equilibrium previous-year questions →

Rankbit System
JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%) | JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%)