DIY Science Projects

Sky-high soda: Who knew that Mentos and diet Dr. Pepper could cause such a mess? Photo by Scott Courtnay-Smith

Bored? Want to make a minor mess and learn something at the same time? Do try these experiments at home (with a parent's permission, of course).

Exploding soda fountain:

We've all seen the baking-soda volcano. It's a classic example of an experiment that can be performed with common kitchen ingredients. While non-damaging and safe explosions are fun in any respect (if planned), this one seems a little meek.

In perhaps the best use of diet soda and Mentos we've ever seen, here's a similar experiment that makes a sky-high eruption — and a pretty big mess.

Note: Absolutely do this outside, away from anything that wouldn't benefit from splatters of soda (for example, a laundry-laden clothesline). Also, diet soda is not essential, but keeps the experimenters from getting too sticky from the sugar. Regardless of stickiness, the soda will splatter, so make sure to wear old clothes.
Here's what you need for your "eruption":

• 1 roll of Mentos (keep wrapped until right before the experiment in order to construct your "candy chute").

• 2-liter bottle of diet soda

• index card

• construction paper

• scissors

• Scotch tape
Here's what to do:

1. The Mentos must be stacked in a neat column, with minimal space between them, so that they can be dropped all at once into the bottle. Make a "candy chute" by cutting a small piece of paper about the length of the package of Mentos and about four inches wide.

2. Wrap the paper around the Mentos package to form a tube. Tape it so it holds its shape. Now you have your chute.

3. Take everything outside! Open your soda bottle. Everything will happen fast once you get started, so make sure that you set everything up.

4. Place the index card over the opening of the soda bottle, then place your chute on top of that so that the end of the chute lines up with the opening of the bottle.

5. Fill your chute with the Mentos and let the adults run away to a safe place.

6. Open your full 2-liter bottle of diet soda. Remove the index card quickly, and let the Mentos drop into the bottle.
Why it works:

Bottled soda contains carbon dioxide that's dissolved in liquid. When the bottle is opened, pressure is released, making the gas bubble out of the liquid, which is what makes soda fizzy.

A few different things happen when the candies are dropped into the soda, but here's the most significant factor in the eruption: When the Mentos fall into the bottle, they start to dissolve, releasing ingredients like gelatin and gum arabic into the soda. Those two things lower the surface tension of the soda (like softening an egg shell) making it easier for the bubbles in the liquid to expand and escape.

Ice cream in a bag:

Almost everyone likes ice cream, except the lactose intolerant, of course. Wouldn't it be nice to make your own? You can, and you don't even need your own ice cream churn; just a few bags, some ice and salt and the desire to shake things up.

This is a fun and delicious experiment that must be done in an area where it's OK to spill a little milk. After all of the ingredients are combined and it's time to shake the bags, it's best to wear gloves — the bag may be cold enough to damage your skin. Go ahead and throw on a scarf and a hat, too … just to be silly.
Here's what you need:

• 1/2 cup milk

• 1/2 cup of heavy whipping cream

• 1/4 cup sugar

• 1/4 tsp vanilla

• 1/2 to 3/4 cup of rock salt

• 2 cups ice

• 1-quart zipper bag

• 1-gallon zipper bag

• measuring cups and spoons
Note: Make as many recipes as you want. Also, experiment with flavors — add chocolate syrup or chocolate chips, for example.
Here's what to do:

1. Put the sugar, milk, cream and vanilla into the quart bag. Seal the bag very securely — and we mean very. Salt water can ruin the ice cream!

2. Put 2 cups of ice into the gallon bag.

3. Add salt to the bag of ice.

4. Place the sealed quart bag inside the gallon bag of ice and salt. Seal the gallon bag very securely.

5. Rock the gallon bag from side to side. Throw it around! Dance a little!

6. Continue to rock and roll until the liquid ice cream has firmed up into solid(ish) ice cream.

7. Remove the quart bag, scoop out your ice cream and enjoy.
Why it works:

Salt lowers the freezing point of ice. By lowering the temperature at which ice is frozen, the milk mixture can freeze (at a temperature below 32 degrees Fahrenheit) into ice cream. So, why do you need to shake the bag anyway? The motion breaks up larger ice crystals, making a smoother ice cream.

(Thanks to SaraKate and Abby Makoviney for helping with these experiments and deciding that science is "delicious and fun.")

who: kids-science-experiments.com/

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