Baking Soda vs. Baking Powder: What Happens When Acids and Bases Mix

Research Questions:

• What happens to pancakes in the absence of leavening agents?
• What happens to pancakes cooked with too much baking soda?
• Describe the chemical reactions of baking soda and baking powder when used as a leavening agent.

In a laboratory, acids and bases are kept separate. In extreme cases mixing common household acids, such as bleach, and bases, like ammonia, can react to produce harmful chemicals. However, acid-base reactions are very common. Acid reflux occurs when acids within the stomach rise back into the esophagus causing the sensation: “heartburn.” Milk of Magnesia, Alka-Seltzer, and Pepto-Bismol are bases used to neutralize the stomach acids. Another common acid-base reaction is in the kitchen. Baking soda and baking powder are used as leavening agents that make breads and other baked goods light and fluffy. In this experiment students will examine the differences between baking soda and baking powder and how the acid-base reaction plays a vital role.

Materials:

• Flour
• Baking powder
• Baking soda
• Half teaspoon Salt
• One and a half tablespoon Sugar
• Two Eggs
• Butter
• Two cups Buttermilk
• Butter
• Camera
• Ruler
• Scale (mg) – can be found in a chemistry laboratory
• Timer

Experimental Procedure:

1. Combine one cup of flour, half teaspoon of baking powder, pinch of salt and sugar, one egg, and one cup of buttermilk in a large bowl. Make four identical batches of the batter and label: A, B, C, and D.
2. Combine one cup of flour, pinch of salt and sugar, and one egg in a large bowl. Make three identical batches and label: E, F, & G.
3. Preheat a griddle at low-medium heat. For each pancake use a quarter cup of batter and cook for 90 sec. on each side. You should cook at least two pancakes per batch.
4. Cook batch A as is.
5. Add a quarter tablespoon of baking soda to batch B, mix thoroughly for five min. and cook.
6. Add a half tablespoon of baking soda to batch C, mix thoroughly for five min. and cook.
7. Add a quarter tablespoon of baking soda to batch D, mix thoroughly and set aside for 30 min. then cook.
8. Add one cup of buttermilk to batch E, mix thoroughly for five min. and cook.
9. Add half teaspoon of baking powder to batch F, mix thoroughly for five min. and cook.
10. Add half teaspoon of baking powder and one cup of buttermilk to batch G, mix thoroughly for five min. and cook.
11. Take a photo of each pancake, noting the color and texture.
12. Cut the pancake in the center and measure its thickness using a ruler. Take a photo of each cross-section with the ruler for reference.
13. What happened to each of the batches?
14. Which batch produced the thickest pancake?
15. Which batch produced the thinnest pancake?
16. Which batch produced a brown colored pancake?
17. What were the differences between batch E and F?

Terms/Concepts: Leavening; Baking soda – sodium bicarbonate; Baking powder; Acid; Base; Maillard Reaction

References:

Joy of baking: baking soda