Difference Between Pure Substance and Homogeneous Mixture

Pure Substance vs Homogeneous Mixture

Matter is composed of different substances, like atoms and other molecules, that have volume and mass. All physical objects are made up of chemical substances which are unchanging in chemical composition and characteristics.
A chemical substance is also known as a pure substance because its elements cannot be physically separated without breaking its chemical chain. Its chemical composition is fixed, and it has individual properties and can occur in solid, liquid, gaseous, or plasma states. A few examples of pure substances are water, gold, salt, sugar, and diamonds.
When pure substances are combined together, these substances form a mixture. Mixtures are composed of two or more pure chemical substances in which their elements and compounds are mixed together giving them various compositions. They can either be heterogeneous or homogeneous.

In a heterogeneous mixture, two or more phases are present. So its components are easy to identify such as in carbonated beverages like cola which is a combination of liquid and carbon dioxide gas. In a homogeneous mixture, the composition is uniform such as in the case of blood which is a combination or mixture of liquid or fluid and blood cells.

While a pure substance cannot be separated physically, the components of a homogeneous mixture can be separated through mechanical and thermal processes such as distillation, sifting, filtering, and crystallization. The individual characteristics of each substance are kept even if they have formed other substances such as suspensions, solutions, alloys, and colloids. The properties of its pure substance components are displayed, and its composition is changed according to the proportion of its components.

Water cannot be separated into hydrogen and oxygen but will only produce water vapor when distilled. Its appearance, density, and color are uniform throughout. Blood, on the other hand, can be separated into red and white blood cells and plasma.
While pure substances have sharp melting and boiling points, meaning the temperature does not change until all its components have melted, the components of homogeneous mixtures melt at different temperatures.

Summary:

1.A pure substance is a form of matter that has a fixed chemical composition and a distinct characteristic while a homogeneous mixture is a mixture of two or more compounds with compositions that are uniform or mixed together in such a way that they are indistinguishable from each other.
2.A pure substance cannot be separated into two or more substances by any means while a homogeneous mixture can be separated into two or more substances through physical or mechanical processes such as distillation, filtration, or sifting.
3.While both a pure substance and a homogeneous mixture have uniform compositions throughout, it is impossible to extract the components of a pure substance while the pure substances that make up a homogeneous mixture can be extracted because they retain their properties even when mixed together.
4.The components of a homogeneous mixture melt or boil at different temperatures while the temperature when boiling or melting a pure substance does not change until all the pure substances have boiled or melted.

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