Chemical Reactions: Understanding the Indications

Which of these observations is an indication that a chemical reaction has occurred?

A. Steam forms above boiling water.

B. A solid forms when a clear solution is frozen.

C. A solid forms when two clear solutions are mixed.

D. Sugar crystals form on the sides of a boiling pot of sugar water.

Answer

A solid forms when a clear solution is frozen, indicating a chemical reaction.

An indication that a chemical reaction has occurred is when a solid forms when a clear solution is frozen.

This observation suggests that the substances in the solution have undergone a chemical change, resulting in the formation of a new substance with a different physical state.

For example, water freezes to form ice, which is a solid, indicating a chemical reaction has taken place.

Chemical reactions involve the breaking and forming of chemical bonds between atoms, leading to the creation of new substances.

Understanding these indications can help us identify when a chemical reaction is taking place, which is essential in various fields such as chemistry, biology, and medicine.