The combination of vinegar and baking soda produces water and carbon dioxide gas. When you combine these two substances in an enclosed container, pressure builds up. If the pressure is released on one side, the container will move quickly in the opposite direction. You can use this principle to build a rocket car from a toy car and an empty plastic water bottle with a cork in it. Tape the bottle to the car, combine the fuel ingredients, and watch the car race away. This project is a graphic demonstration for children about chemical reactions.
Fit the cork tightly into the opening of the water bottle. If it is too loose, you can wrap tape around the cork to make it fit better.
Tape the empty water bottle to the top of the toy car. Lay the bottle down along the top of the car with the opening of the bottle pointed toward the rear of the car.
Make a fuel packet. Place two tablespoons of baking soda into the middle of a square of toilet paper. Fold the square up tightly so that it doesn't come apart easily and so that baking soda does not leak out. Also make sure the packet will fit easily through the bottle's opening.
Put on safety glasses and pour one cup of vinegar into the bottle.
Drop in a packet of baking soda and quickly seal the opening with the cork.
Immediately put the car on the ground pointing in the direction you want it to travel. In a few seconds the toilet paper will dissolve in the vinegar. As the baking soda and vinegar mix, this will create carbon dioxide gas, building up pressure in the bottle. When the pressure is sufficient, the cork will pop out of the bottle to the rear and the car propel forward.
You can reuse the rocket car if the bottle does not have any leaks in it. Try substituting lemon juice for the vinegar. Build two cars and race them with a friend.
Always do this project outside. The car will travel quite far and the cork will pop out with a great deal of force. In addition, it will leave a trail of foam spewing out the back as the car travels. Always wear your safety glasses to prevent any injury from the cork or foam spewing out.