AFOQT Practice Test

What kind of change occurs when sugar dissolves in water?

1. Chemical change

2. Physical change

3. Biological change

4. Mechanical change

The correct answer is: Physical change

When sugar dissolves in water, a physical change occurs because the process involves a change in the state of matter without altering the chemical composition of the sugar itself. In this instance, sugar molecules are surrounded by water molecules and distributed throughout the solution, but the individual sugar molecules remain intact. This type of change is reversible; if the water were to evaporate, the sugar could be recovered in its original form. The essential aspect of a physical change is that while the appearance and form of the substances involved may change (for example, sugar appears to 'disappear' in water), their chemical identities do not. This distinguishes physical changes from chemical changes where the substances undergo a transformation that produces new chemical entities. Biological changes refer to alterations that involve living organisms or their processes, which is not applicable here. Mechanical changes typically involve physical processes such as cutting or grinding without a change in chemical composition, but again, this is not representative of the dissolution process taking place with sugar and water.