Valentine’s Day is a great opportunity to inspire your student’s LOVE for science! Engage your kids with science concepts such as diffusion, density, and surfactants. These three, hands-on science projects include the Dancing Conversational Hearts, Rainbow Heart, and Marbled Valentine’s Day card.
Carbon dioxide gas is created when the vinegar and baking soda reacts. The carbon dioxide gas creates bubbles that attach to the candy and lifts it to the surface of the solution. The carbon dioxide bubbles pop when they reach the surface. Because the hearts are too dense to float, they sink back to the bottom.
The candy is coated with artificial dyes that easily dissolve in water. When the candy is placed in water, molecules in the dye break away from the candy and spread out into the water. The process of molecules spreading out is called diffusion. The molecules in the dye spread away from areas with high concentration to areas with low concentration until the concentration of dye molecules is equal. This is called equilibrium.
The shaving cream is made of a mixture of soap and water. Soap is a surfactant, which means its molecule has a hydrophilic (water loving) and hydrophobic (water repelling) end. Liquid food coloring is hydrophilic. When you drop the food coloring on the shaving cream, it won’t get soaked in, as it can only interact with the hydrophilic parts of the soap molecules and is repelled by the hydrophobic parts.
When you put the paper on top of the color pattern, the food dye gets soaked into the paper, transferring the whole pattern onto its surface. This is because paper mainly consists of cellulose found in cell walls of green plant cells: a hydrophilic molecule. The food dye can spread easily across the paper, creating a beautiful marbled pattern.