Clues that a Chemical Reaction has Occuured

It may be hard to recognize that a chemical reaction has occurred but there are some indicators that tell you for sure. Some reactions produce a distinct smell or odor that may indicate when a reaction is occurring. an example my be if you go outdoors after a thunderstorm, you may detect an unusual odor in the air. The odor is an indication that lightning has caused a chemical change in the air.A change in temperature may also indicate a chemical reaction such as the temperature is higher near logs burning in a campfire. A change in color is often an indication of a chemical change. For example, fruit may change color when it ripens. Formation of bubbles as shows a reaction has taken place. The formation of gas bubbles is another indicator that a chemical change may have occurred.
Formation of a solid or precipitate shows a chemical reaction has taken place When two liquids are combined, a solid called a precipitate can form. The shells of animals such as clams and mussels are precipitates. They are the result of a chemical change involving substances in seawater combining
with substances from the creatures.