Physical and chemical properties describe the characteristics of matter, but they differ in how they are observed and whether the substance changes its identity.
Physical Properties
- Physical properties are characteristics of a substance that can be observed or measured without changing its chemical identity.
- These properties describe the appearance, state, and measurable traits of matter.
- Examples:
- Color
- Odor
- Density
- Melting point and boiling point
- State of matter (solid, liquid, gas)
- Solubility
- Electrical or thermal conductivity
Example: Ice melting into water shows a physical change, because the chemical identity (H₂O) remains the same.
Chemical Properties
- Chemical properties describe a substance’s ability to undergo chemical changes that transform it into a different substance.
- They can only be observed when a substance reacts with another substance.
- Examples:
- Flammability (ability to burn)
- Reactivity with acids or bases
- Rusting of iron (reaction with oxygen)
- Tarnishing of silver
- Ability to decompose
- Combustion behavior
Example: Wood burning into ash and smoke shows a chemical change, because new substances are formed.
Key Difference:
- Physical properties can be measured or observed without changing the substance’s identity.
- Chemical properties can be observed only when the substance changes into a new substance.