Pure and Impure Flashcards
what is a pure substance and its characteristics?
A pure substance is a material that has a uniform and definite composition. It consists of only one type of particle, which can be either an element or a compound. Pure substances have consistent properties throughout and do not vary in composition.
Types of Pure Substances
Elements:
These are substances that cannot be broken down into simpler substances by chemical means.
Each element is made up of only one kind of atom.
Examples include oxygen (O), hydrogen (H), carbon (C), and gold (Au).
Compounds:
Compounds are substances formed when two or more elements chemically combine in fixed proportions.
They can be broken down into their constituent elements through chemical reactions.
Examples include water (H₂O), carbon dioxide (CO₂), and sodium chloride (NaCl).
Characteristics of Pure Substances
Fixed Melting and Boiling Points: Pure substances have specific melting and boiling points.
Uniform Composition: The composition is the same throughout the material.
Homogeneous Properties: They exhibit the same physical and chemical properties throughout.
What is a impure substance and its characteristics?
An impure substance is a material that contains two or more different types of particles or components. The composition of impure substances can vary, and they do not have uniform properties.
Examples of Impure Substances
Mixtures:
Mixtures consist of two or more pure substances that are physically combined but not chemically bonded.
They can be homogeneous (uniform composition) or heterogeneous (distinct, separate components).
Examples include air (a homogeneous mixture of gases) and salad (a heterogeneous mixture of vegetables).
Alloys:
Alloys are mixtures of two or more metals, or a metal and a non-metal, that have been melted together to form a solid solution.
Examples include bronze (copper and tin) and steel (iron and carbon).
Characteristics of Impure Substances
Variable Composition: The proportions of the components can vary.
Variable Melting and Boiling Points: Impure substances do not have fixed melting and boiling points; instead, they may have ranges.
Different Properties: The physical and chemical properties can differ based on the composition of the mixture.
