Inorg. CHem Question

[letsgfuad]

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So according to my book the solubility rules for SO4 2- in H2O is
All salts of Sulfate SO4 2- are H2O soluble except Ca2+, Sr2+, Ba2+, Pb2+.

Then one of my Kaplan questions is:

Questions 18 and 19 refer to the following information:
Ksp
CaSO4 2.4 x 10–5
BaSO4 1.5 x 10–9
AgI 8.5 x 10–17
CuBr 5.9 x 10–9

Which salt is the most soluble in water?
A. CaSO4
B. BaSO4
C. AgI
D. CuBr
E. Cannot be determined from the information given


How is the answer A? I understand the Ksp values, but the question is for water. My notes say CaSO4 is insoluble in water??????

 

[Gasedo]

So according to my book the solubility rules for SO4 2- in H2O is
All salts of Sulfate SO4 2- are H2O soluble except Ca2+, Sr2+, Ba2+, Pb2+.

Then one of my Kaplan questions is:

Questions 18 and 19 refer to the following information:
Ksp
CaSO4 2.4 x 10–5
BaSO4 1.5 x 10–9
AgI 8.5 x 10–17
CuBr 5.9 x 10–9

Which salt is the most soluble in water?
A. CaSO4
B. BaSO4
C. AgI
D. CuBr
E. Cannot be determined from the information given


How is the answer A? I understand the Ksp values, but the question is for water. My notes say CaSO4 is insoluble in water??????

Water possesses all of the below intermolecular forces. For a substance to dissolve in water, it must possess them as well. Also, when dealing with substances other than water, it must have the same set of forces to be solvable. Remember, like dissolves like!

Dispersive Forces are net attractive forces generated by temporary charge imbalances among molecules. Every molecule has dispersive forces.

Dipolar Forces describe the interaction between molecules with dipole moments. To ascertain which molecules have a dipole moment, you must be able to label it as either polar or non-polar. Next, you must draw dipole moments based on electronegativity differences between atoms. If the dipoles do not cancel each other out the molecule has a dipole moment and possesses dipolar forces.

Hydrogen Bonds are special bonds between an atom of hydrogen and either flourine, oxygen, or nitrogen. Again, the Lewis Structure must be drawn to ensure the hydrogen is bonded directly to one of these atoms.

Also answer A. has the highest value for Ksp. The highest its value, the more soluble!

 

[taloddar2002]

This question is a little tricky because all of the listed compounds are practically insoluble in water. However, it asks you to choose the one that is the most soluble. In this question CaSO4 is the most soluble of the listed insoluble compounds. Hope this helps!

 

[letsgfuad]

This question is a little tricky because all of the listed compounds are practically insoluble in water. However, it asks you to choose the one that is the most soluble. In this question CaSO4 is the most soluble of the listed insoluble compounds. Hope this helps!

Ok that makes sense. basically all are very insoluble but due to the ksp alone then i need to chose off of that. Thanks