Most of the pure substances that you encounter in your daily life have been made pure by people through refining. It has the same composition no matter where it comes from. Gold is made up of gold atoms. There are no other elements or compounds added to gold.
They are formed deep within Earth in only a very few areas. All the particles in a diamond are the same. Considered a pure substance if the water contains only hydrogen and oxygen. Pure water is difficult to find in nature. Even the clearest spring water contains dissolved minerals. In nature, pure substances tend to mix with other substances. Although there are a multitude of uses for baking soda, in its simplest form, it is not contaminated with any other chemical compounds.
One of the most common household chemicals. Pure sodium chloride is an ionic crystal solid. In the case of oxygen elemental or oxygen gas , the components are just oxygen and nothing else.
A mixture is a material made up or more than one substance, where the substances are not bonded to each other. In the gas of oxygen gas O2 , all you have is oxygen bonded to other oxygen molecules all floating around together. That being said, we think that when many people ask this question, they are thinking more about the air that we breath. Air is a mixture of multiple substances that are not bonded to each other, including but not limited to oxygen, nitrogen, boron, carbon dioxide, and more.
As discussed right above this paragraph, oxygen is not a mixture. It is a pure substance, in both its elemental and gaseous forms. Air, on the other hand, is a mixture. Any given spoonful of soup will contain varying amounts of the different vegetables and other components of the soup. A homogeneous mixture is combination of two or more substances that are so intimately mixed that the mixture behaves as a single substance.
Another word for a homogeneous mixture is solution. Thus, a combination of salt and steel wool is a heterogeneous mixture because it is easy to see which particles of the matter are salt crystals and which are steel wool. On the other hand, if you take salt crystals and dissolve them in water, it is very difficult to tell that you have more than one substance present just by looking—even if you use a powerful microscope.
On the right, the salt crystals have dissolved in the water so finely that you cannot tell that salt is present. The homogeneous mixture appears like a single substance.
Identify the following combinations as heterogeneous mixtures or homogenous mixtures. Ordinary table salt is called sodium chloride. It is considered a substance because it has a uniform and definite composition. All samples of sodium chloride are chemically identical. Water is also a pure substance. Salt easily dissolves in water, but salt water cannot be classified as a substance because its composition can vary. You may dissolve a small amount of salt or a large amount into a given amount of water.
A mixture is a physical blend of two or more components, each of which retains its own identity and properties in the mixture. Only the form of the salt is changed when it is dissolved into water. It retains its composition and properties. A phase is any part of a sample that has a uniform composition and properties. By definition, a pure substance or a homogeneous mixture consists of a single phase.
A heterogeneous mixture consists of two or more phases. When oil and water are combined, they do not mix evenly, but instead form two separate layers. Each of the layers is called a phase. Identify each substance as a compound, an element, a heterogeneous mixture, or a homogeneous mixture solution.
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