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Cooking is fun and it’s a great way to make a tasty snack. But have you ever thought about what’s going on when you cook something? Try making some cupcakes, and you’ll pick up a thing or two about chemistry.

Safety: This activity requires a hot oven. Ask an adult for assistance. When dealing with food, use clean hands and clean equipment. Ensure cupcake batter is cooked before eating.
First aid: If you burn yourself, put the burn under cool, running water for 20 minutes.

You will need

Ingredients

• Butter
• Eggs
• Self-raising flour
• Caster sugar
• Milk
• Vanilla essence

Equipment

• Oven

  

• Muffin tray
• Patty pans
• Measuring cups and spoons
• Fork
• Mixing bowls
• Kitchen scales
• Metal spoon

  

• Microwave
• Cooling rack
• Oven mitts

What to do

1. Preheat the oven to 200°C.
2. Line the muffin tray with patty pans.
3. Use the scales to weigh out 125 g of butter. Melt the butter in the microwave and set it aside to cool.
4. Use the fork to beat 2 eggs in a small mixing bowl.
5. Mix 2 cups of self-raising flour and ³⁄₄ cup of sugar in another mixing bowl.
6. Add 2 cups of milk, the butter, eggs and 1 teaspoon of vanilla essence to the bowl containing the flour and sugar. Mix it all with a spoon.

   

7. Spoon the mixture into half of the patty pans, leaving the other half empty.
8. Put on you oven mitts and put the muffin tray in the oven. Bake the filled patty pans in the oven for 15 minutes.
9. Remove the cupcakes from the oven with your mitts and cool them on a cooling rack.
10. Turn the oven down to 150°C. Allow the oven and cupcakes to cool.
11. Spoon the remaining mixture into the empty patty pans. Cook these filled patty pans for 15 minutes.
12. Remove the next batch of cupcakes from the oven, allow them to cool, then compare them to the first batch. What do you observe?

What’s happening?

The cupcakes rise due to a chemical reaction. The self-raising flour contains a solid acid and base. When the mixture is wet, the acid and base react to form carbon dioxide gas. The gas bubbles cause the cupcakes to rise. Another reaction, called the Maillard reaction occurs at the same time resulting in the browning of the cupcakes.

Chemical reactions are affected by temperature. By raising the temperature, chemical reactions that cause the rising and browning of cupcakes occur at a faster rate. By lowering the temperature, these reactions don’t occur fast enough, resulting in uncooked cupcakes.

Applications

Using temperature to control chemical reactions in food is at the core of cooking. Cooking at higher temperatures cooks food faster, but might burn the food or result in unwanted flavours.

Many chemical processes used in industry, such as extracting some metals from ores, won’t happen at all unless high temperatures are used.