Write a paragraph explaining your understanding of physical and chemical changes. Provide a specific example of each and explain the evidence that supports your analysis that a physical or chemical change has occurred.

Answer 1

Physical changes refer to alterations in the physical states or properties of matter, such as shape, size, or phase, without changing its chemical composition. They are usually reversible. An example of a physical change is melting ice. When ice is heated, it changes from a solid state to a liquid state, but its chemical composition remains the same. The evidence that supports this analysis is that if the liquid water is cooled, it will solidify back into ice. On the other hand, chemical changes involve the rearrangement of atoms to form new substances with different chemical properties or compositions. These changes are usually irreversible. A common example of a chemical change is burning paper. When paper is burned, it undergoes a chemical reaction called combustion, leading to the formation of new compounds (ash, smoke, and gases). The evidence supporting this analysis is that once paper has burned, it cannot be converted back into its original form by simply cooling or reversing the process.