Final answer:
In a chemical change, a new substance is formed, while in a physical change, no new substance is formed. Chemicals are used to initiate or facilitate chemical changes. Molecules in a chemical change interact through chemical reactions, while in a physical change they may only rearrange or change their state.
Step-by-step explanation:
In a chemical change, a new substance is formed, while in a physical change, no new substance is formed. This is a key difference between the two types of changes. For example, when wood burns, it undergoes a chemical change and transforms into ash and smoke, which are different substances. On the other hand, when ice melts to form water, it is a physical change because no new substance is formed.
Additionally, in a chemical change, the molecules of the substances involved in the reaction interact with one another, often by breaking and forming new chemical bonds. This is different from a physical change where the molecules may rearrange or change their state, but they do not undergo any chemical reactions.
Finally, it is important to note that chemicals are used in chemical changes to initiate or facilitate the reactions. These chemicals, known as reactants, are transformed into new substances, called products, during a chemical change.
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