Lecture Notes: Physical vs Chemical Properties

Definition of Properties

Properties: Characteristics of substances.
Physical Property: Describes characteristics that do not change the chemical identity of the substance.
Chemical Property: Describes characteristics that will change the chemical identity of the substance.

Boiling Point: The temperature at which a substance boils. Example: Water boiling from liquid to gas remains H2O.
Melting Point, Freezing Point, Vaporization: Changes in the state of matter without changing chemical identity.
Ductility: The ability to be stretched into a wire (e.g., copper remains copper).
Malleability: Ability to be hammered into sheets (e.g., aluminum remains aluminum).
Color: Intrinsic color is a physical property. However, a color change can indicate a chemical reaction.
Viscosity: Resistance to flow (e.g., honey vs water).
Density: How closely packed atoms are in a matter.
Mass, Weight, Volume: Related to the physical quantity or space occupied by a substance.

Flammability: Ability to burn, which changes chemical identity (e.g., paper to CO2 and water).
Corrosiveness: Ability to cause corrosion, involving chemical reactions (e.g., acid stripping electrons from metals).
Combustibility: Ability to combust, requiring a chemical reaction (e.g., gasoline reacts with oxygen).
Explosiveness: Related to reactions that release energy rapidly (e.g., TNT).
pH: Indicates the acidic or basic strength, affecting reactivity.
Taste: Relates to chemical reactions with taste receptors (e.g., sour taste due to acidity).

Physical properties relate to state changes without altering chemical identity.
Chemical properties involve chemical reactions and changes in identity.
A physical property does not describe how a substance reacts, whereas a chemical property does.

Understanding the difference between physical and chemical properties helps in identifying how substances interact and transform.