We have opened the fridge and pulled out the oil-vinegar salad dressing, only to see the oil floating on top of the vinegar. Thinking the salad dressing ruined until the bottle is agitated and the oil and vinegar mix together and the salad dressing is saved. But why do the liquids separate in the first place. Some say that it is because oil and water (which is found in vinegars) do not mix.
It is the same thing that occurs when we see news of an oil spill in the ocean. Where the oil floats on top of the ocean. But the tar, which is also found with the oil, does not. It sinks. Tar is oil, and if oil and waters do not mix, then why won’t the tar also float.
That is because things float and sink because of density. That is the relationship between the things mass to the volume that it takes up. Where the heavier (more dense) will sink, and the lighter (less dense) will float, even when the thing is a liquid. For liquids, this concept of density is done related to the density of water. Where the value that we use for this density is of liquids are called “Specific Gravity” of the liquid.
In this lab activity, we will get a chance to examine the relationship of densities of various household liquids. Where students get to explore the concept of gravity while making their own liquid rainbow.