Thank you for the opportunity to help you with your question!
An effective solvent is one that has a stronger affinity for molecules composing a solid than the molecules in the solid do for each other. For example:
NaCl, sodium chloride, is a solid at room temperature. It is an ionic solid, and the interactions between Na+ and Cl- ions in a NaCl crystal are extremely polarized. In order to disrupt the Na+ Cl- interaction in a crystal and thus dissolve the salt, a polar solvent is needed. Water has a strong dipole moment, with a positive "end" to the molecule (towards the hydrogens) and a negative "end" (towards the oxygen). Water is a good solvent for NaCl because the positive "end" of water can surround the Cl- atoms in the NaCl crystal, and the negative "end" of water can surround the Na+ atoms, effectively pulling them apart, dissolving them, or solvating them.
In general, remember the saying "like dissolves like":
- a polar solvent (like water or ethanol, for example) will dissolve an ionic solid or a solid composed of molecules with a dipole moment
- a non-polar solvent (like hexanes, benzene, or many other organic solvents) will dissolve a solid composed of all the same type of atom, or of non-polar molecules such as oils.
Please let me know if you need any clarification. I'm always happy to answer your questions.
Aug 31st, 2015
Are you studying on the go? Check out our FREE app and post questions on the fly!