What Are Some Signs to Look for When Determining If a Chemical Reaction Has Taken Place?

There are a few telltale signs that can help indicate that a chemical reaction has taken place; these include the creation of one or more new substances and a noticeable energy change from the reaction site. However, telling whether a chemical reaction has actually taken place is not always very easy to observe.

These changes can be noted in two different ways, through appearance changes and energy changes.

Appearance changes:

  • Gas is released
  • A solid appears or disappears
  • There is a color change

Energy changes:

  • The temperature changes
  • Light or flames are seen
  • Sound is heard

It is important to note that these signs are merely indicators, not proof, that a reaction has taken place and that the only true sign that a chemical reaction has occurred is the creation of one or more substances as a result of the chemical interaction.