* Chemical Change: A chemical change involves the formation of new substances with different properties. This often involves breaking and forming new chemical bonds. Chemical changes are usually accompanied by changes in temperature (heat released or absorbed).

* Physical Change: A physical change alters the appearance or state of a substance but does not change its chemical composition. Examples include melting, freezing, boiling, condensing, or dissolving.

So, if you mix two substances and the temperature remains the same, it's possible that:

* A physical change occurred: The substances simply mixed without reacting chemically. Think of mixing salt and pepper – they remain salt and pepper.

* A chemical change occurred, but the heat change was very small: Some reactions release or absorb very little heat, making it difficult to notice a temperature change.

Here's how to tell if a chemical change might have occurred:

* Look for other signs of a chemical change:

* Color change: Did the mixture change color?

* Gas production: Did bubbles form, indicating gas release?

* Precipitate formation: Did a solid form and settle out of the mixture?

* Odor change: Did the mixture develop a new smell?

In conclusion, a constant temperature doesn't definitively rule out a chemical change. Look for other signs to determine if a new substance has formed.