Sidewalk Splatter Art
In this activity, we are going to create sidewalk masterpieces using simple chemical reactions! These explosive paint rockets will get messy, so we highly recommend doing this activity outdoors, wearing protective eyewear, and choosing clothing that can get messy!
Let’s Begin!
Learning Objectives/Opportunities
Build basic knowledge about chemical reactions!
Science process skills: observing, predicting, and testing
Developmental Skills: colors, fine and gross motor skills
Materials:
Cornstarch
Water
Food Coloring
Alka Seltzer Tablets - make sure an adult is helping you with this material!
Film Canisters (or another type of small container with poppable cap, needs to be able to be airtight. Mini M&M containers should work too if they still carry those in stores)
Poster Board (optional, if you want to make your art on something so you can keep your painting, otherwise you can decorate the pavement!)
Instructions:
To make paint mix equal parts cornstarch and water (you don't need a lot). This makes a chalk paint, so it's perfect for doing outside on the driveway or sidewalk!
Fill each container about a third of the way with paint.
Add a drop of food coloring to each container then put the cap on tight and shake it to mix.
Break the Alka seltzer tablets into quarters.
Place one small piece of the tablet into the container, put the cap on tight, and then place cap-side down on the poster board or ground. You can try to quickly do a bunch of them at once, or do one at a time!
Step back and watch the paint explosion!
Breaking Down the Science
In this activity, we used a simple chemical reaction to create paint rockets. The cornstarch, water, and food dye create sidewalk chalk paint. Alka-seltzers are tablets that contain solid forms of an acid (citric acid) and a base (sodium bicarbonate). When these tablets dissolved in water, the acid and base combine, causing a chemical reaction that produces gas bubbles. You can observe this reaction if you drop an Alka-seltzer in water like the picture here.
All those tiny bubbles are full of gas. Usually, the gas produced disperses into the air around you, but when this chemical reaction takes place in an air-tight container like a film canister or M&M dispenser, the gas becomes trapped creating tons of pressure. Eventually, with enough pressure, the gas will force the container to open, resulting in the explosive reaction we observe. When it explodes, it flings the sidewalk paint in all directions creating our beautiful sidewalk masterpieces!
Gentle Disclaimer: Adult supervision and guidance is recommended for STEMSpark activities. We may use materials or ingredients in our experiments that can stain surfaces or clothing, be messy, or slippery. Please be careful and make sure no experiments are put in the mouth and kept away from children under 3.