Changing properties

The video explains the chemical reactions that occur when baking a cake, highlighting how baking powder reacts to form carbon dioxide, which helps the cake rise. It contrasts these irreversible chemical changes with reversible physical changes, such as melting and solidifying chocolate, illustrating the differences between the two types of changes.

What role does carbon dioxide play in the baking process?

• It adds flavor to the cake.

• It helps the cake rise and become fluffy.

• It makes the cake firm.

• It cools down the cake.

What happens to the proteins in eggs when they are heated?

• They harden and make the cake firm.

• They melt and become liquid.

• They dissolve in water.

• They evaporate into the air.

Why can't a baked cake be turned back into batter?

• Because it is a physical change.

• Because it has lost moisture.

• Because it is too hot.

• Because it is an irreversible chemical change.

Which of the following is an example of a reversible change?

• Frying an egg

• Baking a cake

• Burning wood

• Melting chocolate

What is a key difference between chemical and physical changes?

• Physical changes involve heat, chemical changes do not.

• Chemical changes are irreversible, physical changes are reversible.

• Chemical changes are reversible, physical changes are not.

• Physical changes create new substances, chemical changes do not.