Shaving cream is one of the unique substances that can exist in all three states of matter: solid, liquid, and gas. When in a can, the cream is a mixture of soap and water that is compressed as a gas. When the can is sprayed, the cream is released as a solid, which eventually condenses to a liquid. Let’s explore some basic, but fun activities with shaving cream!
Molding with Cream
- 1 Can of corn starch
- 1 box of corn starch
- Large bucket or container
What to do
- Dump an entire box of corn starch into the bucket
- Over the corn starch, spray an entire can of shaving cream
- Mix the contents of the bucket (I prefer using my hands) until the mixture appears to be dough-like
- Enjoy molding into different shapes!
Hydrophobic or Hydrophilic Cream?
- 1 Can of shaving cream
- A paper plate
- Card Stock Paper
- Food coloring
- A clear cup or glass
- Spray Bottle with water
What to do
- Fill the glass 2/3 full with water.
- Lightly spray shaving cream on the surface of the water until the glass is full.
- Add a couple drops of food coloring to the surface of the shaving cream and observe.
- Using the spray bottle, spray water onto the surface of the shaving cream and observe.
- Spray shaving cream onto the surface of a paper plate with care to cover the entire surface.
- Flatten the shaving cream so that an even layer is present on the paper plate.
- One drop at a time, carefully drop four drops of food coloring on to the surace of the shaving cream. Be sure to change colors each time and to place the drops at random.
- Use a toothpick to swirl the colors in the foam and create difference designs. Track the displacements of the colors.
- Place the sheet of card stock directly on to the colors, wipe off the shaving cream, and observe the image.
- Spray water from the spray bottle onto the remaining shaving cream on the plate. Observe what happens.
Why this Happens
A hydrophobic substance is one that fears or, repels water. A hydrophilic substance is one that loves water or, attracts water. Shaving cream is both hydrophobic and hydrophilic because of its components: water and soap. Soap is a very hydrophilic substance that reacts with water (the food coloring in this experiment), to draw out only the dye in food coloring. Since soap is hydrophilic, it attracts water and leaves the dye to seep through the shaving cream. The hydrophilic ends of the dye however are more attracted to paper, and therefore attached to the card stock when they were in contact. Soap also has a dual property, and acts hydrophobic as well. This proposal gives an explantation for the dye that remained on the surface of the shaving cream, rather than seeping through.
The spray bottle serves as an equalizer, because it returned the shaving cream back to its original white color. This phenomenon occurs because the water sprayed by the spray bottle attracts the dye that was on the surface of the shaving cream.