Question

NaCl is purified by adding HCl to a saturated solution of NaCl (317 g/L). Will pure NaCl precipitate when 30 mL of 4.5 M HCl is added to 0.15 L of saturated solution? Group of answer choices NaCl will precipitate from solution No NaCl will precipitate

Answer 1

Answer:

If you add concentrated HCl solution to a saturated NaCl solution, you will drive the equilibrium of equation 1) back to the left by increasing the concentration of Cl-(aq). As a result, NaCl will re-crystallize in the solution. This is a demonstration of Le Châtelier’s principle that states: if a system in equilibrium is disturbed, it will shift the equilibrium to counteract the disturbance.

1) NaCl(s) ↔ Na+(aq) + Cl-(aq)

2) HCl(aq) ↔ H+(aq) + Cl-(aq)

K= Ksp = [Na+(aq)][Cl-(aq)]

Ka =

[Cl-(aq)] = Ka[HCl(aq)]/[H+(aq)]

Ksp / [Na+(aq)] = Ka[HCl(aq)]/[H+(aq)]