Add green food coloring. Add blue food coloring. The team was interested in studying the salinity or saltiness of the water. On the way back to the laboratory, the labels came off the samples. One difference in the water samples is the density.
Density is the weight per unit volume or weight for the same amount.
The salty ocean water would be more dense than the fresh water because it has more salt. Because the water samples are not clean, we will not taste them. One way we can investigate the density of these samples is to see which water samples mix and which samples layer one on top of the other. Food coloring has been added to help you see the different water samples. By placing drips of the unknown solutions into clear drinking straws, we can see which layers mix and which layers do not easily mix.