Matter exist in nature as pure substances and mixtures. Pure substances are not very common. The vast majority of substances are mixtures. 

Analyze the following classification to understand better the classification



Image result for libretext pure substances and mixtures



Pure substances and Mixtures

Substances can be pure or impure.

Pure substances

Pure substances are the ones that have a definite composition, this means that if we take a sample from different zones in the substance, the properties will be the same. 

They can be identified by their intensive properties. Example: Boiling and Melting point, density, etc. 

Elements are pure substances: Elements cannot be broken into simpler substances because they contain only one kind of atoms. Examples: H2, O2, Cl2, Na, Ne, Ar, etc.

These elements can be found in the periodic table.

solids liquids and gases as pure elements

Compounds are pure substances: Compounds that can be broken in simpler substances because they are formed by 2 or more atoms combined together. Examples: water, sulfuric acid, sodium chloride, ethanol, etc

compounds pure substances

Impure Substances

Mixtures are NOT pure substances

When two or more compounds or elements are mixed together, we have a mixture. 

Heterogeneous Mixtures

Their properties very throughout the substance

heterogeneous mixture

Homogeneous Mixtures - Solutions

Their properties are the same in any point of the substance. Homogeneous mixtures are also called solutions. Example: Sea water, brass, bronze, etc. These mixtures can be solid, liquid or gases

homogeneous mixtures



Classify the following substances in pure substances (elements or compounds) and mixtures (homogeneous or heterogeneous).


pure substance

 salt water      
 isopropyl alcohol       
 carbon dioxide      
 table salt      
 carbon dioxide      
 sulfuric acid      
 silver nitrate          
© Analia Sanchez