If you want to have a smaller explosion, consider buying a smaller bottle, such as a 20 oz bottle. But a 2L bottle is the standard size used in these experiments and the geyser will last longer than in a smaller bottle.
You should also consider decorating or drawing on the paper to make it resemble a volcano. For this you will need markers, colored pencils or crayons. You will also need tape, glue and a pair of scissors to secure the construction paper around the bottle.
Take an index card and form it into a rounded shape, so it looks like a chute. You will use this to pour all of the Mentos into the soda bottle at the same time. You can tape the index card together so it retains its circular shape.
If you have an old tray or cutting board, you can also use this as the base of your volcano. If you are performing this experiment for a school project, make sure your surface is portable and can fit into the car or bus that takes you to school. [2] X Research source
If you have brown construction paper, consider drawing on it so it resembles a volcano. Many volcanoes have ridges, so you can draw some of these in black or green, so they stand out against the brown shade of the paper. You can also consider adding trees or other elements of green to the paper.
Shape the paper so it has a narrow, circular opening around the mouth of the bottle and a wide, circular opening at the bottom. You will have to overlap the paper at the mouth of the bottle to make it more narrow. If you don’t have enough paper to cover the bottom of the bottle, add an additional piece of construction paper to cover the gap. You can attach it will clear Scotch tape so it will be hard to see.
Buy some cardboard. If you add paper mache to the construction paper, you will need to reinforce it with a sturdier material, like cardboard or poster paper. [4] X Research source Cut out the cardboard in 3 pieces. You might need a pair of box cutters to cut through the material. Each piece doesn’t have to be in a cone shape like the paper. They just have to be wide enough and tall enough to hold up the paper when you wrap it in a cone shape. Try four inches in width and six inches in height to begin with. Use a sturdy form of glue (like Elmer’s) to attach the cardboard to the cone-shaped construction paper. Put aside to let it dry while you prepare to make the paper mache mix. Make the mix for paper mache. Take 1 cup water and 1 cup flour and mix them together in a bowl. Stir with a spoon or whisk thoroughly until all of the lumps are gone from the mixture. [5] X Research source Add a few tablespoons of salt to prevent the mixture from becoming hardened into a mold. Stir until dissolved. [6] X Research source Cut 20-30 strips of newspaper that are long enough to cover the cone shape of the volcano. Soak half of these in the mixture for 5 minutes so they can be fully covered. [7] X Research source Apply one layer (or 10-15 strips) onto the cone. You can apply the strips horizontally or vertically, whichever you prefer. Make sure they lie flush against each other so you have no gaps or puckering between the strips. [8] X Research source Allow time to dry completely (20-30 minutes). Try to make sure you first layer is even and cover the cone entirely. While you are waiting for it to dry, go ahead an add the additional strips to the mixture. Apply a second layer of strips to the cone after the first layer has dried. It is very important that the first layer is dry before you add additional strips. Allow the second layer to fully dry. [9] X Research source Decorate the paper mache cone. Paper mache tends to hold paint or spray paint well, so these could both be options. You can pick a traditional volcano color, like brown or green, but you could also consider bolder colors if you want something less realistic, like gold, silver or orange. Place the cone back over the Diet Coke bottle. Since it will be free standing with the support of the cardboard, you won’t need to tape it to the bottler. Make sure the opening of the cone is big enough to access the cap on the mouth of the bottle.
If you are using a surface like a tray or cutting board, be careful not to draw anything permanent on the surface that could damage it. Avoid attaching the soda bottle to the surface. If you glue it to the surface, this could damage the surface or tip over the bottle once it explodes from the Mentos. Instead, simply place the bottle and its cone-shaped decoration on the surface shortly before you plan to complete the experiment.
You can also wear a rain coat or another water resistant piece of clothing to protect you.
Ideally you should pick a location with a durable surface that is far from any buildings or cars. A concrete area such as a school’s parking lot or outdoor courtyard would be a great location.
If you want the explosion to occur at a slightly slower rate, then crush up the Mentos before you drop them into the bottle. You will probably need a knife to help crush and cut up the four Mentos. If you are an elementary school student, ask an adult for help with this step.
Although the carbon dioxide gas bonds with water molecules in soda, it is still trying to escape from the liquid when it is not in a pressurized container. You can see this when you pour soda from a bottle into a cup – the gas creates a slight foam or fizz as it escapes the water and touches the air. [12] X Research source
Mentos candies have very small pits in their shells. As the candy sinks to the bottom of the soda bottle, these pits increase the activity of the carbon dioxide gases in the soda. When the candies hit the bottom of the bottle, all of the gas that has been building up is released and the soda explodes from the bottle. [13] X Research source
Try rinsing the Mentos in water first before adding them to the soda bottle. This will change the texture of the candies’ shells. How does this compare to the earlier explosion with normal, whole Mentos? Check for changes in temperature. Do the results of the experiment alter when the bottle of soda has been chilled? What if the bottle has been left in the car on a hot day?[14] X Research source Compare the height of the geyser in different experiments. If you can, try to set off the geyser near a wall or the side of building (only do this if you have a hose so you can wash the side of the building afterwards). Try to mark the height of the geyser each time you perform the experiment. Do you see any difference in the range of height? (You may need a building with a second story window or a fire escape to gauge this).
