Physical Versus Chemical Changes Explained

The video explains the differences between physical and chemical changes. Physical changes alter the appearance but not the substance, such as cutting hair or mixing salt and water. Chemical changes create new substances and involve breaking or forming chemical bonds, with indicators like burning, temperature change, explosions, color change, odor change, and fizzing. The video provides examples and indicators to help identify these changes.

What is a characteristic of a physical change?

• A new substance is formed.

• The appearance changes but the substance remains the same.

• Chemical bonds are broken.

• It always involves a temperature change.

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

• Burning wood

• Baking a cake

• Melting ice

• Rusting iron

What happens during a phase change?

• The substance changes color.

• Chemical bonds are formed.

• The substance changes state but remains the same chemically.

• A new substance is created.

What defines a chemical change?

• It involves a change in state.

• It creates a new substance by altering chemical bonds.

• It is always reversible.

• It only affects the appearance.

Which of the following is NOT an indicator of a chemical change?

• Change in color

• Change in odor

• Formation of bubbles

• Change in shape

What does a temperature change without external heating or cooling indicate?

• A chemical change

• A phase change

• A mixture

• A physical change

Which indicator suggests a chemical change has occurred when two substances are mixed?

• The mixture changes color.

• The mixture remains the same.

• The mixture becomes colder.

• The mixture separates into layers.