20. Consider the following solutions. In each case, predict whether the solubility of the
solute should be high or low. Justify your answer.
a KCl in H2
O d H2
O in CH3
OH
b HF in H2
O e NH4
Cl in C5
H12
c KCl in CCl4 f CCl4
in H2
O�
a) KCl in H2O: High solubility. KCl is an ionic compound that dissociates in water, forming ions that are able to interact with the polar water molecules, resulting in a high solubility.
KCl in CH3OH: Low solubility. CH3OH is a polar solvent but it has weaker polarity and lower dielectric constant than H2O, thus it cannot effectively solvate the ionic K+ and Cl- ions, resulting in a low solubility.
b) HF in H2O: High solubility. HF is a polar molecule that can form hydrogen bonds with water, resulting in a strong solvation of the HF molecules, and hence high solubility.
c) NH4Cl in C5H12: Low solubility. C5H12 (pentane) is a nonpolar solvent and is unable to solvate the ionic NH4+ and Cl- ions effectively, resulting in a low solubility.
d) H2O in CH3OH: High solubility. Both H2O and CH3OH are polar solvents that can form hydrogen bonds with each other, resulting in high solubility.
e) NH4Cl in CCl4: Low solubility. CCl4 is a nonpolar solvent and cannot form strong electrostatic interactions with the ionic NH4+ and Cl- ions, resulting in low solubility.
f) CCl4 in H2O: Low solubility. CCl4 is a nonpolar solvent and incompatible with the polar H2O solvent, resulting in low solubility.