Equilibrium

Chemistry · Class 11

Simulation · Chemistry · Class 11

Why some salt solutions are not neutral

"Why some salt solutions are not neutral" is a free, interactive Class 11 Chemistry simulation for NEET and JEE, built on the NCERT section "Common ion effect and hydrolysis of salts" in Equilibrium. Choose the parent acid and base of a salt; the ions that react with water are animated and the solution pH is computed, including pH = 7 + ½(pKa − pKb) for weak/weak salts. NEET has asked about this idea 3 times in 10 years of papers. JEE Main asked 52 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).

From the lesson Common ion effect and hydrolysis of salts in Equilibrium. Change the values and watch what happens.

Why some salt solutions are not neutralChemistry · Class 11

What it shows

NCERT § "Common Ion Effect in the Ionization of Acids and Bases"; § "Hydrolysis of Salts and the pH of their Solutions"

Choose the parent acid and base of a salt; the ions that react with water are animated and the solution pH is computed, including pH = 7 + ½(pKa − pKb) for weak/weak salts.

Controls

5 to try

  • Segmentedparent acid strong / weak
  • Segmentedparent base strong / weak
  • SliderpKa 3–10
  • SliderpKb 3–10
  • Slidersalt concentration 0.001–1 M

Try this

Make a weak acid–weak base salt that is exactly neutral (pKa = pKb); then make an NH4Cl-type salt (strong acid, weak base, pKb 4.75) and read its acidic pH at 0.1 M (≈5.1).

Common mistake

Every salt solution is neutral; Ka and Kb of a conjugate pair are unrelated.

In NEET

10 years of papers

Asked 3 times in 10 years of NEET.

See the past questions: pH and Buffer Solutions, Equilibrium (chapter)

In JEE Main

42 shifts analysed

52 questions from Equilibrium across the 42 JEE Main shifts Lumi has analysed (2017–2026).

See the past questions

The idea behind it

NCERT § "Common Ion Effect in the Ionization of Acids and Bases"; § "Hydrolysis of Salts and the pH of their Solutions"

  • Adding an ion already present in a weak electrolyte's equilibrium pushes the equilibrium back and suppresses ionisation; adding CH₃COONa to acetic acid lowers [H₃O⁺] and raises pH.
  • The common ion effect is a direct application of Le Chatelier's principle.
  • Salts of a strong acid and a strong base (NaCl) do not hydrolyse and give neutral solutions.
  • Salts of a weak acid and a strong base (CH₃COONa) hydrolyse to give basic solutions.
  • Salts of a strong acid and a weak base (NH₄Cl) hydrolyse to give acidic solutions.
  • For a salt of a weak acid and a weak base (CH₃COONH₄), pH = 7 + ½(pKa − pKb); the solution is neutral only if pKa = pKb.
  • Hydrolysis is the reaction of a salt's cation or anion (or both) with water, which changes the pH away from 7.

Questions

5 answers

What does the "Why some salt solutions are not neutral" simulation show?
Choose the parent acid and base of a salt; the ions that react with water are animated and the solution pH is computed, including pH = 7 + ½(pKa − pKb) for weak/weak salts.
What mistake does the "Why some salt solutions are not neutral" simulation fix?
A common mistake it clears up: every salt solution is neutral; Ka and Kb of a conjugate pair are unrelated.
Has NEET asked about this idea?
Yes. NEET has asked about this idea 3 times in 10 years of papers.
Does JEE Main ask questions from Equilibrium?
Yes. JEE Main asked 52 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
Is this simulation free?
Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Common ion effect and hydrolysis of salts" in Equilibrium (Class 11 Chemistry).

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