Question

chopping wood vs burning wood—watch the animation and look at the before and after images.

chopping wood	burning wood
is this a physical or chemical change?	is this a physical or chemical change?
explain using evidence	explain using evidence

Explanation:

Chopping Wood:

• What do you notice about the particles? The particles (wood) are just broken into smaller pieces; their chemical identity remains the same.
• Is this a physical or chemical change? Physical change.
• Explain using evidence Chopping only changes the size/shape of wood. No new substance is formed (e.g., the wood still has the same chemical properties, like being combustible in the same way, and its elemental composition doesn’t change).

Burning Wood:

• What do you notice about the particles? The wood particles react with oxygen, forming new particles (like ash, smoke, CO₂, H₂O vapor) with different properties.
• Is this a physical or chemical change? Chemical change.
• Explain using evidence Burning produces new substances (ash, gases). The wood’s chemical structure is altered (e.g., cellulose in wood breaks down, reacts with O₂, and forms compounds with different properties than wood).

Final Table (Filled):

Chopping Wood	Burning Wood
Physical change	Chemical change
Evidence: No new substance (only size/shape changes; wood’s chemical properties remain)	Evidence: New substances (ash, CO₂, etc.) formed; wood’s chemical structure altered

Answer:

Chopping Wood:

• What do you notice about the particles? The particles (wood) are just broken into smaller pieces; their chemical identity remains the same.
• Is this a physical or chemical change? Physical change.
• Explain using evidence Chopping only changes the size/shape of wood. No new substance is formed (e.g., the wood still has the same chemical properties, like being combustible in the same way, and its elemental composition doesn’t change).

Burning Wood:

• What do you notice about the particles? The wood particles react with oxygen, forming new particles (like ash, smoke, CO₂, H₂O vapor) with different properties.
• Is this a physical or chemical change? Chemical change.
• Explain using evidence Burning produces new substances (ash, gases). The wood’s chemical structure is altered (e.g., cellulose in wood breaks down, reacts with O₂, and forms compounds with different properties than wood).

Final Table (Filled):

Chopping Wood	Burning Wood
Physical change	Chemical change
Evidence: No new substance (only size/shape changes; wood’s chemical properties remain)	Evidence: New substances (ash, CO₂, etc.) formed; wood’s chemical structure altered