Question

key concepts
4 identify give an example of a physical change and an example of a chemical change.
5 compare how is a chemical change different from a physical change?
6 apply suppose a logs mass is 5 kg. after burning, the mass of the ash is 1 kg. explain what may have happened to the other 4 kg.

Explanation:

1. A physical change example is melting ice (change in state without new - substance formation). A chemical change example is burning wood (new substances like carbon dioxide and ash are formed).
2. A chemical change results in the formation of new substances with different chemical properties, while a physical change only alters physical properties like state, shape, or size without forming new substances.
3. When the log burns, it undergoes a chemical reaction. The other 4 kg of mass is likely converted into gaseous substances such as carbon dioxide and water vapor that escape into the air during the combustion process.

Answer:

1. Physical change: Melting ice. Chemical change: Burning wood.
2. Chemical change forms new substances; physical change only alters physical properties.
3. The 4 kg is likely converted into gaseous substances that escape during combustion.