|MadSci Network: Chemistry|
Hi Mindy: I would like to answer your question in two parts. First what SHOULD have happened, and then what PROBABLY happened. Everyone has heard the saying "like dissolves like". It refers to the miscibility or mixing ability of liquids. Liquids can be separated into two groups, polar and nonpolar. Polar liquids like water, kool-aid, and milk will completely mix with one another. "like dissolves like". Nonpolar liquids like gasoline and oil will mix together, again "like dissolves like". However, polar and nonpolar liquids will not mix. So if you mix oil with water, no matter how hard you shake it or how hard you stir it, they will separate and form two distinct layers. First, what SHOULD have happened: The polar maple syrup goes right to the bottom because it is very heavy, or dense. When the oil, which is nonpolar, and will not mix with maple syrup was added, it became the top layer because it is less dense. Next, the red-dyed water is added. Water is polar, so it won't mix with the oil. It is more dense than the oil, but less dense than the maple syrup, so it should have settled between the two. The layers should now be maple syrup on the bottom, red-dyed water above it, and the oil on top. Now, we add the blue-dyed alcohol. Alcohol is unique because it has both polar and non-polar parts. Slowly adding the alcohol to the top, it should have become the very top layer because it has a polar part that doesn't want to mix with the oil and it is less dense than the oil, so it should remain on top. Final view, maple syrup on bottom, red-dyed water next, oil next, and on top the blue-dyed alcohol. Next, what PROBABLY happened. The first mixings went as planned. We have maple syrup on bottom, red-dyed water next, and oil on top. If the alcohol was introduced in such a way that the oil was mixed with it (ie rapidly pouring it in, or shaking the container), the oil could dissolve in the alcohol. The alcohol will mix with the water because they are both polar. We no longer have separation of layers because we dissolved our only non-polar liquid into a polar one and now they are all polar and can all mix. The maple syrup probably stayed on the bottom unless it was stirred. Of course when the dyes mixed, a darker color (blue/purple)was formed. Coincidentally, did you notice that you can only dye the polar liquids (water and alcohol) and not the nonpolar one (oil)? This is because the dye itself is polar and won't dissolve in a nonpolar liquid. Hope this helps!! Chemistry: The Central Science, Brown, LeMay and Bursten, Prentice Hall, 1997, pp463-465.
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