The density of water at 25 °C is 0.997 g/ml and the density of vegetable oil at this temperature is 0.970 g/mL. Oil and water do not mix, so when 5 mL of each liquid is poured into a test tube, two layers form. Which layer is found on the top?
The correct answer and explanation is :
The layer that is found on top is the vegetable oil.
Explanation:
When two liquids are poured together in a test tube and do not mix, the liquid with the lower density will float on top of the liquid with the higher density. This principle is based on the fact that denser substances are “heavier” and thus sink, while less dense substances are “lighter” and will float.
In this case, the densities of the two liquids are provided:
- Density of water at 25°C is 0.997 g/mL.
- Density of vegetable oil at 25°C is 0.970 g/mL.
Since vegetable oil has a lower density than water, it is less “heavy” and will float on top of the water when they are combined. This is because the molecules in the oil are not as tightly packed as the molecules in the water, which is why the oil occupies more space for the same mass and is therefore less dense.
In the test tube, the water (which has a density of 0.997 g/mL) will form the bottom layer, while the vegetable oil (which has a density of 0.970 g/mL) will form the top layer.
This concept is similar to how oil floats on water when you see them together in a container. Even though both liquids are in equal volumes (5 mL each), the difference in their densities dictates the layering, with the denser water sinking below and the less dense vegetable oil floating above.
So, to summarize: vegetable oil, with a density of 0.970 g/mL, will form the top layer, and water, with a density of 0.997 g/mL, will form the bottom layer.