In this worksheet, we will practice describing the solvation mechanisms of molecules and ionic solids and the enthalpic and entropic changes involved.
Why are and ions strongly solvated in water but not in hexane?
- AWater molecules are bent, so ions can occupy the space between bonds. Hexane molecules are straight so cannot interact with ions in this way.
- BHexane molecules are much larger than water molecules, so they cannot pack around the small sodium and chloride ions as easily as water can.
- CDissolution of ions in hexane is entropically costly, as interactions with ions force the hexane molecules into less flexible folded conformations.
- DIon-dipole forces between the ions and water are stronger in total than the ionic bonds of sodium chloride. Hexane is non-polar so interacts with ions far more weakly.
- EChloride ions deprotonate water molecules, and the resulting ion-ion interactions are stronger in total than the ionic bonds of sodium chloride. Hexane cannot be deprotonated so interacts with ions far more weakly.
Fill in the blanks. Typically, as the temperature of the solvent increases, solids become soluble, and gases become soluble.
- ALess, less
- BMore, more
- CLess, more
- DMore, less