Everyday Einstein discusses water's ability to dissolve in Part 3 of this series on the amazing superpowers of water.
One of water’s nicknames is “the universal solvent.” This simply means that a lot of things dissolve in water. If you’ve been following along with my series on water, you might have guessed that the reason behind water’s ability to be an amazing solvent is its ability to form hydrogen bonds.
Just to quickly refresh your memomy, what's most important to remember is that water molecules are formed when one oxygen atom forms covalent bonds with two hydrogen atoms. The oxygen atom shares one electron with each hydrogen atom, which in turn share one electron each with oxygen, forming a water molecule.
However, since these shared electrons tend to spend more time on the oxygen side of the molecule, this leaves oxygen with a partial negative charge and the hydrogen atoms with partial positive charges. These partial charges allow water molecules to form hydrogen bonds or polar bonds with one another. These bonds are the source of water’s amazing powers, including its ability to dissolve so many things.
Let’s Mix Things Up
First, what does it mean to dissolve anyway? If I drop some salt or sugar into my water, does it disappear? When we dissolve something into water, we’re taking the molecules of that substance and mixing them into the molecules of water. If we want to be really scientific, we’d say that the thing were dissolving is called the solute and thing we’re dissolving it into is the solvent. Together, the solute and the solvent make what’s called a solution. Something that can be dissolved in water is said to be water-soluble.
A solution sounds a lot like a mixture, but it’s a bit different. If you pour a bag of chocolate chips into some cookie dough, the chocolate chips aren’t chemically bonded to the cookie dough. (If they are, you might want to double-check that recipe). When we combine two things together that aren’t chemically bonded, we call this a mixture.