JEE Main 2013 · 22 April · Online · Chemistry · Ionic Equilibrium
Which one of the following arrangements represents the correct...
Which one of the following arrangements represents the correct order of solubilities of sparingly soluble salts Hg2Cl2,Cr2(SO4)3, BaSO4 and CrCl3 respectively?
Options
ABaSO4>Hg2Cl2>Cr2(SO4)3>CrCl3
BBaSO4>Hg2Cl2>CrCl3>Cr2(SO4)3
CBaSO4>CrCl3>Hg2Cl2>Cr2(SO4)3
DHg2Cl2>BaSO4>CrCl3>Cr2(SO4)3
Correct answer
B. BaSO4>Hg2Cl2>CrCl3>Cr2(SO4)3
Step-by-step solution
Cr2(SO4)3⇋2Cr++++3SO4−−Ksp=(2s)2(3s)3=4s2×27s3=108s5s=(108Ksp)1/5Hg2Cl2⇋2Hg2++2Cl−Ksp=(2s)2×(2s)2=16s4s=(16Ksp)1/4BaSO4⇋Ba+++SO4−Ksp=s2s=KspCrCl3⇋Cr3++3Cl−sKsp=s×(3s)3=27s4s=(27Ksp)1/4Hence the correct order of solubilities of salts is
Ksp>\left(\frac{\mathrm{K}_{\mathrm{sp}}}{16}\right)^{1 / 4}>(27Ksp)1/4>\left(\frac{\mathrm{K}_{\mathrm{sp}}}{108}\right)^{1 / 5}$