Solubility for Dummies

water is a polar molecule

When push comes to shove, it's a safe bet that all of us would prefer to get our information from knowledgeable people instead of people who know as little as us. Well, unless we're fans of conspiracy theorists, but hey – those people "know" what they "know." Be that as it may, when it comes to facts we leaned in middle school to ask the science teacher about science and the art teacher about art, not the other way around. Right? Unfortunately, eHow.com was never built on that model. As witness, we give you graphic artist Christina Hadley (aka Christi Worthington) and her attempt to explain, "Why Mineral Oil & Water Don't Mix" for Sciencing.com.

Had someone who'd taken a chemistry course or two been tasked with answering the question, it's a safe bet that the words "solubility" and "soluble" would appear in the text; neither is present in Hadley's version. Instead, she opened with the nonsensical observation that,

"It’s easy to conclude that mineral oil and water should mix well. They're both clear and odorless."

Well, maybe it was "easy" for Christi to conclude; but for people who know a little about the topic, color and odor aren't indicators of solubility. Once she got that silliness out of the way, Hadley started in on attempts to quote college professors from their class notes, including her interpretation of their far more learned explanations. To wit,

• "Forcing Interaction: When an emulsifier like soap joins with water and oil, their molecules gain something in common that helps them form a bond." – Clearly, she was unaware that to emulsify doesn't mean to "form a bond," it entails making tiny droplets of the oil that will eventually recombine and separate from the water.
• "Polar Molecules... water molecules [have] two ends... one end is positively charged and the other one is negatively charged..." – A water molecule is analogous in shape to a triangle, with an oxygen atom at one vertex and hydrogen atoms on the other two. Triangles don't have "ends."
• "Polar Bonds: ... mineral oil's lighter weight plays a key role in why it won't mix with water water. Its nonpolar bond is not as strong as water's polar bond." – Ummm, no, Christi, relative strength of the bonds isn't why the two don't mix. The fact that mineral oil, an organic compound, isn't polar means that there are no charged locations on the margin that can wedge their way into water's hydrogen bonds.
• "Density: ...Mineral oil’s density is close to the weight of a water strider’s step; it's not dense enough to pull the water molecule's bond apart." – Funny: ethanol has an even lower density than mineral oil, yet it's highly soluble in water. In point of fact, Charles Ophardt of Elmhurst College didn't say what Christi claimed, instead presenting a lesson on how immiscible liquids form layers in a glass.

So our Dumbass of the Day in her infinite dumbassery managed to mangle information harvested from at least three different scientists, once again demonstrating why you shouldn't ask a freelancer with a BA in "design" to explain basic chemistry. Next time, ask a chemist. Hell, ask a physicist or even a paleontologist!

SI - CHEMISTRY