Chemical Reactions:Cake Baking

Chemistry is the study of the composition of substances and their properties and reactions. Baking a cake is a great way to study physical and chemical properties as well as physical and chemical changes. First, I’ll list a few terms that will be introduced:

physical properties: The physical traits of a substance determined by using ones senses: touching, tasting, smelling, seeing, and hearing.

physical changes: Any change in a substances physical traits, such as color, size, odor, taste, etc..

chemical properties: The properties which cause specific behavior of substances during chemical reactions, such as reacts with water, doesn’t react with water.

chemical change (chemical reaction): A process in which one or more reactants are changed into one or more different products.

reactants: The starting substance or substances of a chemical reaction.

products: The substance or substances formed in a chemical reaction.

variable: Any thing that can change the results of a process, such as a chemical reaction.

When baking a cake, the ingredients are the reactants. The final product that can be seen is the cake. Gases are produced that are not visible but can be smelled.

I suggest using a white box cake. Every thing added to the cake mix can change the texture, taste, and/or color of the cake. This means that each ingredient is a VARIABLE. There is an endless number of ways the ingredients can be mixed–add different amounts of oil; add fruit juice instead of water. As chemists, you must measure each ingredient accurately and keep a record of these measurements. Then, record the results for each specific test. You decide on the properties to be recorded. I suggest: color, taste, texture- Does Dad like it?

The Chemistry of Baking a Cake
Baking a cake is a wonderful chemistry experiment. Following are some of the science procedures and concepts involved.
1. Chemicals (ingredients) and equipment are collected.
2. Physical properties are observed, such as: color, texture, and states of matter (solid, liquid, gas).
3. Chemicals are combined to form a mixture (the batter).
4. The temperature of the mixture is increased (cooked in an oven).
5. Physical changes of the mixture can be observed via see-through oven doors.
6. Bubbles lift the batter and pop at its surface. Since you did not add a gas to the mixture, the formation of a gas is an indication that a chemical change is occurring.
7. A chemical change means that new chemicals are formed from the original chemicals that you mixed together. With a cake, you have to heat the mixture for all the chemical reactions to occur.
8. After the cake cools—cut it open and look for evidence that some of the gas bubbles got trapped inside. A gas takes up space so there will be holes in the solid cake where the bubbles were.
9. The chemical reaction causing the bubbles is due to a leavening agent, such as baking powder, which produces carbon dioxide gas when it is mixed with water or any liquid containing water.

Why record all the measurements and results? Because you want to find out what you do and don’t like so you can repeat the mixtures you like most. In other words, as a chemists you are recording your testings so other chemists can repeat them. This is the same thing that cooks do. In other words, as a cook you want to record the recipe that you like so it can be used again later or shared with a friend.

How to get started:

I suggest that you experiment by adding one new ingredient to the cake mix, such as a dry pudding mix. Your objective could be to determine how the amount of pudding mix affects the texture of the cake.

FYI: The objective of any experiment should be to compare two variables. These variables are called: the independent variable (the one you purposely change) and the dependent variable (what changes in response to changes in the independent variable).

1. independent variable: the amount of dry pudding mix (note: you control this change)

2. dependent variable: the texture of the cake (note: this change is in response to changes in the amount of pudding mix used)

Controlled variables: These are variables that could affect the results so you keep them constant. For the cake these variables are all ingredients except the pudding mix, including the amount of dry cake mix, water, oil, or eggs used. Products such as Egg Beaters make it easy to measure a specific amount of egg for each batter prepared. The batter for each mixture must be baked in the same kind of pan at the same temperature and for the same amount of time. Using a muffin pan makes this easy. You could use paper liners that are labeled for each specific batter mixture.

Control: This is a standard to compare the experimental results to. Since your experiment is testing the results of adding pudding mix, your control can be to make the cake batter as directed on the box without adding the pudding mix.

Hypothesis: It is always fun to guess the results, but a scientific guess has to be more than just making up stuff. It is always based on facts that you already know. For this activity you can talk about cakes with different textures, such as a fruit cake, angel food cake, etc…. Kids can be reminded how the texture of these cakes was different. Then they can decide how they think adding pudding mix will affect the cake’s texture. Give choices, such as fluffy and firm.

Results: What affect does adding the pudding mix have on the texture of the cake? Your answer could be something like this:

As the amount of pudding mix ______(increased, decreased) the firmness of the cake’s texture ____(increased, decreased, didn’t change).

Conclusion: Did the results support your hypothesis? Please point out that if the results was different from their hypothesis it doesn’t mean their hypothesis was wrong for all mixtures of cake mix and pudding. Maybe a different kind of pudding would have a different results. Or, maybe a different cake mix. The point is to not emphasize right and wrong hypothesis.

For example:

Hypothesis: The more pudding mix added the fluffier will be the cake’s texture.

Results: As the pudding mix increases, the firmer is the cake’s texture.

Conclusion: The results did not support my hypothesis. I think it is because mom bought a cheap pudding mix (I am being funny–but then this may be the answer–it would fit for me.) I think the cake mix advertised on TV would work better.

Conclusion: The results did not support my hypothesis. I think it is because there was not enough liquid added to the mixture. The control batter was thinner than my experiment batter. I can test this again using different amounts of liquid.

What I want you to obtain from this page is that all experiments can lead to other investigations. Start yourkids to asking “I wonder…..” questions. I wonder…How would more liquid affect the results? I wonder…Would another brand of pudding affect the results?

I am interested in your opinion of the ideas on this page. If you use them, let me know your results. You can email me at:

ASK JANICE