Question

1. why do ionic substances dissolve in water better than nonpolar substances? (p. 3)

Explanation:

Water is a polar molecule with a partial positive charge on hydrogen and a partial negative charge on oxygen. Ionic substances are composed of ions (positive and negative). The polar water molecules can surround the ions: the negative oxygen ends of water molecules attract positive ions, and the positive hydrogen ends attract negative ions, a process called hydration, which stabilizes the ions and helps dissolve the ionic compound. Nonpolar substances have no separated charges, so water molecules (being polar) don't interact favorably with them (due to the "like dissolves like" principle—polar dissolves polar, nonpolar dissolves nonpolar), so nonpolar substances don't dissolve well in water.

Answer:

Ionic substances dissolve better in water than nonpolar substances because water is a polar molecule. Ionic compounds consist of positive and negative ions. The polar water molecules can hydrate (surround) these ions: the partially negative oxygen in $\ce{H2O}$ attracts positive ions, and the partially positive hydrogen attracts negative ions, stabilizing the ions and breaking the ionic lattice. Nonpolar substances lack separated charges, so water (polar) does not interact favorably with them (per the "like dissolves like" principle), leading to poor solubility.