A birthday cake is baked that a physical or chemical change?

Physical Changes:

* Shape: The batter changes shape from a liquid to a solid cake.

* Texture: The cake becomes firm and spongy due to the formation of air bubbles during baking.

* Color: The cake browns on the outside due to the Maillard reaction.

* State of matter: The batter changes from a liquid to a solid cake.

Chemical Changes:

* Cooking: The heat from the oven causes chemical reactions in the batter.

* Proteins: The proteins in the flour and eggs denature, changing their structure and creating the cake's texture.

* Sugars: The sugars in the batter caramelize and contribute to the browning and sweetness.

* Fats: The fats in the batter melt and contribute to the cake's moisture and texture.

* Starches: The starches in the flour gelatinize, thickening the batter.

* Maillard Reaction: This chemical reaction between sugars and amino acids produces the characteristic brown color and flavor of the cake.

* Yeast (if used): Yeast ferments the sugars, producing carbon dioxide gas which makes the cake rise.

Conclusion:

Baking a birthday cake involves a complex interplay of both physical and chemical changes. The physical changes are evident in the outward appearance and texture of the cake, while the chemical changes are responsible for the cake's flavor, texture, and browning.