Understanding Matter: Properties, Substances, and Mixtures

Properties of Matter

Characteristic and General Properties

There are some characteristic properties which allow us to identify substances (e.g., density, conductivity, color) and some general properties common to all types of matter (e.g., mass, volume, temperature).

Pure Substances

Types of Pure Substances

A pure substance is a form of matter with a constant composition that does not change regardless of physical conditions. Pure substances are categorized into two main types:

Compounds

Compounds are pure substances that can be chemically decomposed into simpler substances.

Elements

Elements are pure substances that cannot be decomposed into simpler substances by any chemical or physical procedure.

Examples of Pure Substances

• Compounds: Distilled water, Salt (Sodium Chloride)
• Elements: Iron, Oxygen, Gold, Sulfur, Copper, Lead, Platinum, Tin, Aluminum

Mixtures

Definition of Mixtures

A mixture is a substance formed from the combination of two or more pure substances that can be separated by physical procedures.

Types of Mixtures

Heterogeneous Mixtures

A heterogeneous mixture is a mixture in which components can be distinguished by optical procedures.

Homogeneous Mixtures (Solutions)

A homogeneous mixture, also known as a solution, is a mixture in which no distinction between components is possible by conventional optical procedures.

Examples of Mixtures

• Homogeneous Mixtures: Mineral water, Bronze, Air, Sugar water, Petrol, Steel, Brass
• Heterogeneous Mixtures: Water with sand

Classification of Matter

Category	Pure Substances	Mixtures
Types	Elements, Compounds	Homogeneous, Heterogeneous
Examples	Gold (Element), Distilled Water (Compound)	Seawater (Homogeneous), Sand in Water (Heterogeneous)

Separation of Mixtures

Common Separation Techniques

Screening

Separation of solid particles of different sizes using a sieve.

Filtration

Separation of an insoluble solid from a liquid.

Crystallization

Separation of a dissolved solid from a liquid by evaporating the solvent to form crystals.

Magnetic Separation

Separation of two components when one is ferromagnetic (attracted to a magnet).

Decantation (Settling)

Separation of two immiscible liquids or a solid from a liquid by allowing the denser component to settle.

Distillation

Separation of liquids with different boiling points, or a dissolved solid from a liquid, by heating and condensation.

Chromatography

Separation of mixtures based on the differential affinity of components for a stationary phase and a mobile phase (solvent).

Concentration Calculations

Mass Percent (% m/m)

Mass Percent = (Mass of Solute / Mass of Solution) x 100%

Volume Percent (% v/v)

Volume Percent = (Volume of Solute / Volume of Solution) x 100%

Mass Concentration (Mass/Volume)

Mass Concentration = Mass of Solute / Volume of Solution