Question

use the weak acid HCHO2 to defend or contradict the statement "A weak acid has a stronger conjugate base". Let me know if you are using HCHO2 to defend the statement or contradict it. Then use equations/formulas and no more than 2 sentences to do so.

Answer 1

Answer:

Formic acid can react to water, to give protons to medium:

  HCOOH     +     H₂O   →     H₃O⁺     +           HCOO⁻  

Weak acid         Base          Acid           Strong conjugate base

    HCOO⁻       +     H₂O  ⇄    HCOOH     +  OH⁻                 Kb

Strong base           Acid       Weak acid       Base          

So the formate can take a proton from water to become formic acid again and that's why it is a conjugate strong base.

Explanation:

HCOOH → Formic acid

To determine the conjugate pair and to know if they are weak or strong, we should know, if they can react to water. This is called hydrolisis.

For example: formic acid is a weak acid, so the formed formate will be its conjugate base and it will be strong because the formate can react to water, to make formic again.

Weak acid → Strong conjugate base

Strong acid → Weak conjugate base

Weak base → strong conjugate acid

Strong base → weak conjugate acid

For example HCl is a strong acid. When it is in aqueous solution, we have protons and chlorides.

HCl + H₂O → H₃O⁺  + Cl⁻

Chloride will be the weak conjugate base, because it can't react to water.

We can not make HCl again, according to this equation:

Cl⁻ + H₂O ← HCl + OH⁻    This is impossible.

Formic acid can react to water, to give protons to medium:

 HCOOH     +     H₂O   →     H₃O⁺     +    HCOO⁻

Weak acid         Base          Acid           Strong conjugate base

So the formate can take a proton from water to become formic acid again and that's why it is a conjugate strong base.

    HCOO⁻       +     H₂O  ⇄    HCOOH     +  OH⁻                 Kb

Strong base           Acid       Weak acid       Base