Linette Guare

Layers of Liquid

Concept: Density

Density measures how heavy something is for its size. Liquids of different densities can not be mixed and will separate with the heavier densities at the bottom and the lighter densities at the top. The different objects float at different levels in the liquid depending on their densities.

Materials:

• 4 - 50 mL beakers
• 50 mL corn syrup
• 50 mL vegetable oil
• 50 mL water (dyed with red food coloring)
• 50 mL rubbing alcohol (dyed with green food coloring)
• small bolt, pasta, and cork

Pre-Demo Preparation:

Pour each of the liquids into the 4 separate beakers.

Directions: Place the cylinder on light box.

1. Pour the corn syrup into the cylinder.

2. Pour the oil careful down the side of the cylinder so it doesn't mix.

3. Pour the water the same way, but watch as it settles between the oil and corn syrup.

4. Pour the rubbing alcohol in last.

5. Add various objects such as a small bolt, pasta, and cork.

Introduction:

One of my favorite things to watch at Easter is mixing all the dyed egg colorings together to see what color they become when mixed. But not all liquids can mix together, like these common household liquids.

Explanation:

These liquids do not mix because they have different densities. Density = mass/volume.

The liquids that are more dense are also heavier (per constant volume) and are at the bottom and the liquids that are the least dense will stay on top. Because of the different densities the liquids separate into layers. Corn syrup is the heaviest and therefore is at the bottom. Water is lighter than corn syrup, but heavier than oil and alcohol. The interesting thing that we saw was that even though the oil was added second, the water was heavier than the oil and pushed the oil up to the top. The alcohol is the lightest and stays on top.

The items that are dropped in will settle on the first layer that has a heavier density than itself and under a solution that is lighter than it is. A bolt has a higher density than all the liquids, so it settles at the bottom. The pasta has a higher density than alcohol, oil, or water but lower than corn syrup, so it floats on the corn syrup. A cork is less dense than all of the liquids, so it floats on the surface of the alcohol.

Safety Precautions: None - all household items

Waste Disposal: Dispose of all liquids down the drain.

Reference: Magic Science by Jim Wiese 1998