Difference Between Molecule and Mixture

Molecule vs Mixture

Difference between molecule and mixture is something we need to know when we are examining the concept of matter. Matter can be classified as pure substances and mixtures. Generally, we need both mixtures and pure substances for different purposes in our life. Pure substances are the elements in the periodic table and the molecules formed by reacting two or more elements. This article describes the properties of molecules and the properties of mixtures. Also, mixtures and molecules have many differences than similarities. Here we discuss the difference between molecules and mixtures too.

What is a Molecule?

Pure substances contain only one type of compound. Molecule is the smallest unit of a pure substance , which is responsible for its chemical properties. It has a fixed mass and a definite atomic composition. Molecules can be monoatomic (Inert gases: Neon – Ne, Argon – Ar, Helium – He, Krypton – Kr), diatomic (Oxygen – O2, Nitrogen – N2, Carbon monoxide – CO), triatomic (Water – H2O, Ozone – O3, NO2 – Nitrogen dioxide) or polyatomic (Sulfuric – H2SO4, Methane – CH4). Most of the compounds have more than one atom in their molecules. If a molecule contains only one type of element, they are called homonuclear molecules; Hydrogen (H2), Nitrogen (N2), Ozone (O3) are some examples for the homonuclear molecules. Molecules containing more than one type of elements are called heteronuclear molecules; Hydrogen chloride (HCl), ethane (C2H4), Nitric (HNO3) are some examples for the heteronuclear molecules.

Difference Between Molecule and Mixture

What is a Mixture?

A pure substance contains only one type of molecule. In a mixture, there are two or more pure substances. Substances in a mixture are combined physically, but not chemically. Mostly, physical methods are used to separate compounds in a mixture. In a mixture, each substance keeps their individual properties.

Mixtures can be divided into two groups, namely “homogeneous mixtures” and “heterogeneous mixtures”. The homogeneous mixtures are uniform throughout the mixture on an atomic or molecular level and that of heterogeneous mixtures are not uniform throughout the mixture. Most of the heterogeneous mixtures does not have a unique composition; it varies from sample to sample.

• Homogeneous mixtures: They are called solutions.


Air is a gaseous solution of several gases (O2, CO2, N2, H2O, etc.)

Brass is a solid solution of copper (Cu) and zinc (Zn).


• Heterogeneous mixtures:

Sandy water, oil and water, water with ice cubes in it, salty water (salt is completely dissolved)

What is the difference between Molecule and Mixture?

• Elements react with each other to make a molecule, but compounds in a mixture do not react with each other.

• Physical methods are used to separate components in a mixture, but elements in a molecule cannot be isolated using physical methods.

• Elements become more stable when they form molecules. Example: Sodium (Na) is flammable when it contacts water or it reacts very quickly when it is exposed to the air. Chlorine (Cl2) is a toxic gas. However, sodium chloride ( NaCl) is a very stable compound. It is neither flammable nor toxic.When a mixture is formed, it does not affect the stability of any substances.

• The boiling point of a mixture is lower than the boiling point of any individual substance in the mixture. The boiling point of a molecule depends on several factors (molecular weight, intermolecular weight, intramolecular weight, etc.).

• Molecules can be either homonuclear or heteronuclear depending on the types of molecules present in the molecule. Mixtures are either homogeneous or heterogeneous depending on the uniformity throughout the mixture on an atomic or molecular level.


Molecule vs Mixture

Molecules are pure substances and they contain one or more types of chemical elements. A molecule has a definite molecular weight and a unique chemical formula. Mixtures contain more than two substances in different proportions. Those different substances in a mixture are mixed together, but they are not joined with each other. Each substance in a mixture keeps its own properties. Different substances can be easily identified in a heterogeneous mixture whereas it is difficult to identify different components in a homogeneous mixture.