Misconceptions — Wrong vs Correct Thinking — Notes

#	✗ Wrong Belief	✓ Correct Understanding
1	At equilibrium, concentrations of reactants and products are equal	At equilibrium, concentrations are CONSTANT, not equal — the ratio is fixed by K
2	A catalyst increases the equilibrium constant	A catalyst has zero effect on K — it only lowers activation energy equally for both directions
3	Adding more reactant increases K	K is independent of concentrations — only temperature changes K
4	High K means reaction is fast	K says nothing about rate — it only describes the position of equilibrium
5	pH of 10^{-8} M HCl is 8	pH 8 would be basic; an acid cannot produce pH > 7; correct answer is ~6.98 (water ionization contribution must be included)
6	Neutralisation of strong acid and strong base always gives pH 7	True at 25°C; at other temperatures, Kw changes and neutral pH ≠ 7
7	Strong acid is more acidic than all weak acids at any concentration	At very low concentration, a strong acid can have higher pH than a more concentrated weak acid
8	Common ion effect only applies to Ksp	Common ion effect applies to any weak electrolyte equilibrium, including weak acid ionisation
9	For $Ag_{2}CrO_{4}$ → 2 $Ag^{+}$ + $CrO_{4}^{2-}$ , Ksp = [ $Ag^{+}$ ][ $CrO_{4}^{2-}$ ]	Correct Ksp = [ $Ag^{+}$ ]^{2}[ $CrO_{4}^{2-}$ ]; stoichiometric coefficients become exponents
10	Buffer pH only depends on the ratio [salt]/[acid], not the actual concentrations	Correct — Henderson-Hasselbalch shows pH depends on the RATIO, not individual concentrations; this is why diluting a buffer does not change its pH (ratio unchanged)