What is evidence of a physical change and evidence of a chemical change as is present after a bonfire is that physical change or chemical change? There is a sour smelling liquid present in a cup of milk that was left on the counter for three days, is that physical change or chemical change, a balloon is much smaller after letting the air out is that physical change or chemical change there is a loud sound at a firework word explodes in the air. Is that chemical change or physical change there is a liquid substance in a pot after putting it in a chunk of butter is that physical change or chemical change , there is a on the counter that was originally yellow. Is that physical change or chemical change change

Answer 1

Let's analyze each scenario you've presented to determine whether it represents a physical change or a chemical change.

1. Evidence after a bonfire: After a bonfire, evidence such as ashes and smoke indicates that a chemical change has occurred. In a bonfire, wood undergoes combustion, transforming its chemical structure into gas (smoke) and solid (ash), indicating a chemical change.

2. Sour-smelling liquid in a cup of milk left out for three days: The sour smell indicates that bacteria have acted on the milk, resulting in fermentation and spoilage. This change in the chemical composition of the milk means this is a chemical change.

3. A balloon is much smaller after letting the air out: When the air is released from a balloon, the size of the balloon changes, but the substance (the air) and its chemical composition remain the same. Therefore, this is a physical change.

4. A loud sound when a firework explodes: The explosion of a firework is also a chemical change since the components of the firework undergo a chemical reaction that produces gas, light, and sound. The reaction produces new substances (like gases and hot particles), which are evidence of a chemical change.

5. Liquid substance in a pot after putting in a chunk of butter: If the butter melts and becomes a liquid, this is a physical change. The composition of the butter does not change; it simply changes from solid to liquid state.

6. A substance on the counter that was originally yellow: If the color change is due to a chemical reaction (e.g., if the substance reacts with oxygen or another chemical), this would be a chemical change. If it changes color without a change in composition (like fading due to light exposure), it may be considered a physical change. More context is needed for a precise classification.

To summarize:

• Bonfire: Chemical change
• Sour milk: Chemical change
• Deflated balloon: Physical change
• Firework explosion: Chemical change
• Butter melting: Physical change
• Color change on the counter: Needs more context, possibly physical or chemical change depending on the cause of the color change.