This experiment's a real gas! And you'll see what we mean when you make a bubbly lemon or orange soda that's tasty enough to drink.

What you'll need:
a lemon or orange
a large glass water
1 teaspoon of baking soda
sugar or some other sweetener

What to do:
Squeeze juice from the lemon or orange into your glass, then add an equal amount of water.

Stir in a teaspoon of baking soda. Now take a sip; add some sugar if it's not sweet enough.

What happens:
Your homemade soda will be fizzy and taste like lemon or orange soda.

Why this happens:
All that bubbling is the result of a chemical reaction between a base and an acid. A base is a compound that gives off negatively charged hydrogen ions when dissolved in water, and an acid is a compound that gives off positively charged hydrogen ions when dissolved in water. When you mix the baking soda (a base) with the lemon or orange soda (an acid), they react and produce a fizzy gas called carbon dioxide. (The bubbles in store-bought sodas are also created by carbon dioxide, but they're added under pressure to water.)