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Mixing Molecular MaterialsKeep in mind that molecular materials come in two general categories: polar and nonpolar. Let's start this section by considering combinations of molecular materials that will give solutions. There is an old rule of thumb, a generality, which goes like this: "Like dissolves like." A material which is made of polar molecules will dissolve in other materials which are made of polar molecules. Materials made of nonpolar molecules will dissolve in other things which are made of nonpolar molecules. "Like dissolves like." Conversely, polar materials are generally insoluble in nonpolar materials and vice versa. The reason for this is that all nonpolar molecular materials have van der Waals bonding, and thus all of the intermolecular bonding is of about the same strength. Polar molecular materials have stronger dipole-dipole bonds or hydrogen bonds. Different polar molecular materials will generally mix well with one another, but not with the nonpolar molecular materials. When you try to mix polar and nonpolar molecules together, they generally cluster together and stay bonded with their own type. In this section we will first look at some examples and then consider the bond changes that take place when molecular materials dissolve in one another.
E-mail instructor: Eden Francis Clackamas Community College |
