Made from soda ash, baking soda is a naturally occurring soda bicarbonate with an alkaline base. Approximately 5 percent of lemon juice is citric acid, which accounts for the sour taste of the lemon. When you mix an acid and a base, the result is a chemical reaction that creates a new product, with a neutral base. In the case of lemon juice and baking soda, the new product is carbon dioxide gas, water and salt.

In baking, baking soda serves as a leavening agent. The baking soda causes dough and batter to expand when mixed with an acid, such as lemon juice. Heat during the baking process fosters the release of carbon dioxide when baking soda reacts with an acid. The carbon dioxide expands the surface area of the heated dough, making it light and airy. The more carbon dioxide released, the more the dough rises.

Good recipes contain a harmonic balance of ingredients, often tweaked and adjusted to perfection. Baking is a science, which is why it is so important to follow recipe instructions without making too many changes. This is especially true when it comes to leavening agents. According to the University of Kentucky, the carbon dioxide bubbles that develop during the leavening process can get too big. Eventually, the oversized bubbles combine, the bubbles burst and the dough collapses. If you open up the oven and see a flat cake, you may have added more baking soda than the recipe called for.

The bubbly reaction between baking soda and lemon juice is invaluable when it comes to cleaning. In fact, the two mixed together create an economical and environmentally friendly cleanser. If you are looking for a greener way to clean, sprinkle some baking soda into your toilet bowl, followed by a few sprinkles of lemon juice. Let the concoction sit while you tend to other things. Go back to your toilet later and perform a few swishes with the toilet brush for a sparkling clean shine.

A fun way to view the reaction between lemon juice and baking soda is by carrying out the balloon experiment. Wrap the opening of a balloon around the pointed end of a kitchen funnel. Pour 1 teaspoon of baking soda into the balloon. In an empty water bottle, add the juice of one lemon and about 1/8 cup of water. Remove the balloon from the funnel and wrap the open end around the top of the bottle. As the baking soda falls into the bottle, it will mix with the lemon juice and produce carbon dioxide, which will magically blow up the balloon.