Question: What kinds of evidence indicate a chemical change has taken place? Observe: Some chemical reactions release heat, and others absorb heat. In an exothermic reaction, heat is released and the temperature of the system rises. In an endothermic reaction, heat is absorbed and the temperature of the system decreases.

In the Gizmo, drag the Thermometer into the flask of water.

A.

What is the starting temperature?

B.

Click Play, and wait for the reaction to end. What is the final temperature?

C.

Was this reaction exothermic or endothermic?