Physical and Chemical Change | AP Chemistry - Grade 9 PDF Download

Physical Change

• Physical changes, like melting or evaporating, do not result in the formation of new chemical substances.
• These alterations are typically reversible and do not involve the creation of new compounds.
• Examples include forming mixtures from multiple substances or dissolving solutes in solvents.
• Such changes are categorized as physical because they do not yield new substances and are usually simple to undo or separate.

Chemical Change

• Chemical changes, known as chemical reactions, result in the creation of new substances with distinct properties from the initial reactants.
• Indications of such changes include alterations in color, the formation of a precipitate, or the release of gas bubbles.
• Reversing chemical reactions is often challenging due to the formation of new substances.
• Energy changes occur alongside chemical reactions, where energy can be released (exothermic) or absorbed (endothermic).
• The majority of chemical reactions release energy (exothermic), while only a minority absorb energy (endothermic).