solubility of ionic compounds

[aspiringdoctor1]

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Can someone please confirm if my following logic is correct or not?

Assuming same temperature and equimolar concentrations of NaCl and KI, is it safe to say that more of KI will dissolve in water (KI will have a higher Ksp) without any other information?

My reasoning is that the coulombic force between the cation and anion is weaker for KI than NaCl because KI has larger atomic radii. Thus, the intermolecular forces between solute are more easily overcome.

Thanks guys!

 

[PiBond]

Can someone please confirm if my following logic is correct or not?

Assuming same temperature and equimolar concentrations of NaCl and KI, is it safe to say that more of KI will dissolve in water (KI will have a higher Ksp) without any other information?

My reasoning is that the coulombic force between the cation and anion is weaker for KI than NaCl because KI has larger atomic radii. Thus, the intermolecular forces between solute are more easily overcome.

Thanks guys!

here's my two cents, but it's merely an educated guess.

No, we can't simply use coulombic forces to determine the Ksp of a compound. How easy it is to break apart a salt doesn't translate (necessarily) to how easily it will dissolve in water. We also need to take into account the strength of the bonds that the cation/anion will form with the solvent--and thus we need to consider size of the ions among other things. Therefore, the solvation energy in conjunction with the lattice energy would need to be considered....which is (I believe) manifested in our Ksp values that are determined empirically in lab.

maybe someone will have a more definitive answer

 

[loveoforganic]

Sounds good to me

Edit: @PiBond

 

[Rabolisk]

To add onto what PiBond has already said, not only does one need to consider the enthalpy change H, but also entropy change S, to determine Ksp. Besides, both KI and NaCl are considered to be water-soluble, which means at (relatively) low concentrations, both dissolve fully, or the Ksp is infinite. In reality, of course there is a saturation point for both salts, but that is not knowledge one needs to know.