The 'elephant toothpaste' demonstration involves the rapid decomposition of hydrogen peroxide, producing foam. Is this process an example of a physical change or a chemical reaction?

• A. It is a physical change because only the state of matter changes.
• B. It is a physical change because no bonds are broken or formed.
• C. It is neither a physical nor a chemical change.
• D. It is a chemical reaction because new substances are formed.

Answer: (D)

Verified step by step guidance

1. Understand the difference between a physical change and a chemical reaction: A physical change affects the form or state of a substance without changing its chemical identity, while a chemical reaction involves breaking and forming chemical bonds to create new substances.
2. Analyze the elephant toothpaste demonstration: In this reaction, hydrogen peroxide (H\_2O\_2) decomposes into water (H\_2O) and oxygen gas (O\_2), which are different substances from the original reactant.
3. Recognize that the production of oxygen gas and water indicates that chemical bonds in hydrogen peroxide molecules are broken and new bonds are formed in the products.
4. Note that the rapid formation of foam is due to the release of oxygen gas, which is a new substance, confirming that a chemical reaction has occurred.
5. Conclude that since new substances are formed through bond breaking and formation, the elephant toothpaste demonstration is an example of a chemical reaction, not a physical change.