Consider this reaction: HCO3− + H2S → H2CO3 + HS− Which is the conjugate acid?

H2S
HCO3-

HS–

H2CO3

The conjugate acid : H₂CO₃

Further explanation

Given

Reaction

HCO₃− + H₂S → H₂CO₃ + HS−

Required

The conjugate acid

Solution

Bronsted-Lowry

Acid ⇒ H⁺ + conjugate base

Bases + H⁺⇒ conjugate acids

Acid and conjugate base : H₂S and HS−

Base and conjugate acid : HCO₃− and H₂CO₃

H₂S gives (H⁺), then the remaining acid is a conjugate base  HS−

HCO₃− receives (H +), then the conjugate acid H₂CO₃

Answerthe half-reaction having the greatest tendency to occur at the anode:     i₂(aq) + 2e⁻  ⇄ 2i⁻  ;   e = +0.53 v======oxidation occurs at the anode. we must therefore find the half-reaction with the greatest tendency to oxidize.the given values of e are reduction potentials (the form of the half-reactions are of reduction).the lower the reduction potential, the higher the potential to oxidize. the half-cell with the lowest reduction potential will have the greatest tendency to oxidize at the anode.the half-reaction having the greatest tendency must be    i₂(aq) + 2e⁻  ⇄ 2i⁻    e = +0.53 vbecause its reduction potential is the lowest out of the three.