Rainy Day Blues
Chemistry
Level
1
Two cars are sitting next to each other in a parking lot. The clean, shiny, newly-waxed hotrod has water droplets collecting on its hood, while the dirty pickup truck right next to it does not. Why the difference?
The wax contains non-polar compounds that disrupt the water's intermolecular forces
The dirt contains non-polar compounds that disrupt the water's intermolecular forces
The dirt contains polar compounds that disrupt the water's intermolecular forces
The wax contains polar compounds that disrupt the water's intermolecular forces
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1 solution
Relevant wiki: Surface Tension
Water is a polar molecule, and will interact more strongly with other polar molecules. Dirt contains a combination of polar and non-polar molecules. The car wax, on the other hand, is made up of non-polar, organic components that do not interact with water. The water droplets falling on both cars form spheres due to surface tension, but the polar compounds in the dirt lower that surface tension, causing the water to spread rather than forming beads.