Differences between mixtures and compounds are what I will be discussing in this article. This is to help students in secondary or high school to gain understanding between them. Before I discuss the topic extensively, kindly note that matter may be classified into elements, compounds, and mixtures.
What are compounds
A compound is a substance which contains two or more elements chemically combined together. It is formed as a result of chemical change. It is a new substance with entirely different properties from those of
- The substance(s) from which it was formed
- It component elements
The component elements of a given compound are always present in a fixed ratio by mass. For example,
- Water is a compound formed as a result of a chemical reaction between the component elements, hydrogen and oxygen, in the ratio of 1:8 respectively
- Carbon (IV) oxide is a compound in which the component elements, carbon and oxygen, are in ratio 3:8
Based on the behaviour when exposed to the atmosphere, compounds are classified into deliquescent, hygroscopic, and efflorescent. Also, based on the nature and properties, compounds are also classified as acids, bases, and salts.
Examples of compounds are water, caustic soda, sand, limestone, washing soda, ethanol, common salt, sugar, etc.
What are mixtures
A mixture contains two or more constituents which can be separated by physical methods. The constituents of mixtures can be elements or compounds, or both. In samples of a given mixture, the constituents may be present in different proportions, e.g. different samples of cement contain variable proportions of calcium and aluminum trioxosilicate (IV). The constituents of a mixture retain individual identities because their physical and chemical properties are not changed by simple mixing. Hence, air, which is a mixture of gases, retains the properties of each of the component gases. In fact, many familiar things around us are mixtures.
Based on the number of phases coexisting, mixtures are classified into homogeneous and heterogeneous.
Homogeneous mixtures have their constituents existing in just one phase. These may be sub-divided into:
- Gas-Gas mixtures e.g. air
- Liguid-Liquid mixtures e.g. water-kerosene mixture
- Solid-Solid mixtures e.g. alloys
Heterogeneous mixtures have their constituents existing in at least two different phases. They may also be subdivided into:
- Gas-Liquid mixtures e.g. aerated drinks like beer and soft drinks
- Liquid-Solid mixtures e.g. muddy water, sand-sugar solution
Gas-Solid mixtures e.g. harmattan, solid particles suspended
Examples of mixtures are air, soil, urine, milk, palm wine, sea water, blood, crude oil, brass, etc.
Differences between mixtures and compounds
Below are the major comparisons:
|It may be homogeneous or heterogeneous||It is always homogeneous|
|The constituents are not chemically bound together and can, therefore, be easily separated and recover by physical means||The component elements are chemically bound together and cannot be separated by physical means|
|The constituents can be added together in any ratio by mass. Hence, a mixture cannot be represented by a chemical formula.||The components are present in a fixed ratio by mass. Hence, a compound can always be represented by a chemical formula.|
|The properties of a mixture are the sum of those of its individual constituents.||The properties of a compound differ entirely from those of its component elements.|