Question

4. Consider the following equilibrium: CaSO4 (s) + Ca2+ + SO42- What effect (no change, shift to products, shift to reactants) will the following changes have on this equilibrium? EXPLAIN briefly. a. adding Na2SO4(s) b. adding Na3PO4 (Look at your solubility rules!) c. adding H2O d. adding KC1

Answer 1

CaSO4 (a) = ceapan + 50(09) Kc = [Ca2+] [sod?; adding Na, J04 (Q): Na, 504 dissociates as . L Na, S04 (29) - 2 Nastoo, t 504 (29) After addition of Nag 50409), the concentrations S04 (as) ions increases · Thus, according to Le Chateliai's principle in order to mainlain the constancy of Kcthe above equilibuium shifts in the back-ward direction. Na, 504 Ca504 (8) bacal (29) + S04 (89) A shift in backward direction adding Nag P04 :- Nagp04 dissociates as Na3PO4 — 3 Natrag) + posing After addition Nag PO4, Ca2+ ions is precipitated as ca, (P04), because solubility product of Ca304), is very small (2077x102 such that pcionie produeet) > Ksp { (43(01)2} of (43(PO4), in solution APOTHSCONO M I

HALMASHAURI Thus, due to precipitation of ca3(PO4)3 the concentration of razt decreases · Hence, According to Le-chatelier's principle in order to maintain the constancy of kc , the above equilibrium shifts in the forward direction...e. shifts towards the produel. adding H2O: On addition of H₂O, concentration of free ions decreases. Thus, in order to maintain the constancy of Kc , the above shifts towards The produel- H2O Ca S04 (8) calfaq) + s04 Cary shift in forward oddi adding ke: direction a ku dissociates as Ke(s) KY09) + c 29) ca²f const may be consumed as Ca2+ + 24 = Calle (strong electrolyte cissociates completely into lony) That is there is no effect on concentration ca2fq soq2. Hence, there is no effect on equilibrium after addition of ku. H ome