A container is filled with 0.25 liter of water and 0.75 liter of oil. At first the oil and water appear to mix, but after 10 minutes the oil and water separate as shown. This separation occurs because the
oil -
A. has a greater volume than the water
B. has a greater mass than the water
C. is less soluble than the water
D. is less dense than the water
Hey

Explanation:

Water molecules are polar molecules. That means one end of the molecule has a positive charge and the other end has a negative charge. This allows water molecules to bond together. Oil molecules, on the other hand, are non-polar.

Have you ever dissolved salt in water? How about sugar or coffee grounds? These things mix easily with water because they also have polar molecules. They’re able to bond with the water molecules.

However, non-polar molecules only mix well with other non-polar molecules. This explains why oil doesn’t mix well with water. Their molecules aren’t able to bond.

So what happens when you try to mix oil and water? The water molecules attract each other, and the oil molecules stick together. That causes oil and water to form two separate layers. Water molecules pack closer together, so they sink to the bottom, leaving oil sitting on top of the water.

Have you ever shaken a bottle that contained both oil and water? If so, you know that the two did mix for a short time. That’s because you caused emulsion. You forced the liquids to mix with each other. However, that mixing doesn’t last long! If you look at the bottle again after a minute or so, you’ll see that the water and oil have separated once again.

You can get oil and water to mix together for longer periods. You just have to add an emulsifier. That’s a molecule with one end that has one polar end and one non-polar end. Egg yolks are common emulsifiers. So is soap! It attracts oil on one end and water on the other. That’s what it does when it cleans your hands!

The next time you’re in a restaurant, look for a container of oil and vinegar dressing sitting on the table. Is all the oil at the top? That’s because the vinegar is mixed with water. Give it a good shake and watch what happens!