Chemical Change and Chemical Reaction

Multiple Choice

Burning Wood

• Physical Change

• Chemical Change

What is a Chemical Change?

A chemical change occurs when substances combine to form new substances with different properties. During a chemical change, the atoms rearrange themselves, creating new bonds and breaking old ones. This process often involves the release or absorption of energy, such as heat or light.

​What is a Physical Change?

They occur when a substance undergoes a change in its appearance or state, but no new substances are formed. Physical changes can include processes like melting, freezing, boiling, or dissolving. These changes do not alter the fundamental composition of the substance.

How are they different from eachother?

​Chemical Change

How are they different from eachother?

​Physical Change

​Now, let's explore some evidence of chemical changes.

One common piece of evidence is the formation of a gas. When a chemical change occurs, it can often produce a gas as a byproduct. For example, when vinegar and baking soda are mixed, they undergo a chemical reaction that releases carbon dioxide gas, causing bubbles to form.

Another piece of evidence is the change in color. Sometimes, a chemical change can result in a noticeable color shift. For instance, when an apple is cut and exposed to the air, it undergoes a chemical change that causes it to turn brown. Similarly, when iron rusts, a chemical reaction takes place, resulting in a reddish-brown color.