Which pure substance contains molecules

For example, shops sell cartons labelled as 'pure' orange juice. The label means that the contents are just orange juice, with no other substances added. However, the juice is not pure in the chemical sense, because it contains different substances mixed together. In chemistry:. The table shows some examples:. Pure substances have a sharp melting point but mixtures melt over a range of temperatures. In chemistry, a pure substance consists of only one type of atom, molecule, or compound.

In other disciplines, the definition extends to homogeneous mixtures. Examples of pure substances include tin, sulfur, diamond, water, pure sugar sucrose , table salt sodium chloride and baking soda sodium bicarbonate.

Crystals, in general, are pure substances. Tin, sulfur, and diamond are examples of pure substances that are chemical elements. All elements are pure substances.

Sugar, salt, and baking soda are pure substances that are compounds. Examples of pure substances that are crystals include salt, diamond, protein crystals, and copper sulfate crystals. Depending on who you talk to, homogeneous mixtures may be considered examples of pure substances.

Examples of homogeneous mixtures include vegetable oil, honey, and air. While these substances contain multiple types of molecules, their composition is consistent throughout a sample. If you add soot to air, it ceases to be a pure substance. Contaminants in water make it impure. Heterogeneous mixtures are not pure substances. Examples of materials that are not pure substances include gravel, your computer, a mixture of salt and sugar, and a tree.

If you can write a chemical formula for a substance or if it is a pure element, it is a pure substance! Actively scan device characteristics for identification. Use precise geolocation data. Select personalised content. Create a personalised content profile. Distinguishing between homogeneous and heterogeneous mixtures is a matter of the scale of sampling. On a small enough scale, any mixture can be said to be heterogeneous, because a sample could be as small as a single molecule.

In practical terms, if the property of interest is the same regardless of how much of the mixture is taken, the mixture is homogeneous. Some mixtures can be separated into their components by physical mechanical or thermal means.

Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:. Skip to main content. Introduction to Chemistry. Search for:. Substances and Mixtures. Learning Objective Distinguish chemical substances from mixtures. Key Points Matter can be broken down into two categories: pure substances and mixtures.

Pure substances are further broken down into elements and compounds. Mixtures are physically combined structures that can be separated into their original components.

A chemical substance is composed of one type of atom or molecule. A mixture is composed of different types of atoms or molecules that are not chemically bonded.