What is a pure substance Mixtures and pure substances are not clear about what a substance refers to

Matter is not an element.

Elements and molecules are two different concepts. Elements are macroscopic concepts, molecules are microscopic concepts, matter is made up of molecules, and matter is also said to be composed of elements. Matter refers to molecules, or large aggregates of atoms.

For example, oxygen is a substance composed of a large number of oxygen molecules, and an oxygen molecule is composed of two oxygen atoms, and iron is directly composed of a large number of iron atoms).

A substance composed of one molecule is called a pure substance, and a mixture composed of two or more molecules is called a mixture.

Pure substance: Macroscopic definition: It is composed of the same substance called pure substance, which is divided into elemental substances and compounds.

Microscopic definition: A substance composed of the same kind of molecule is called a pure substance.

It is characterized by a mixture of substances with fixed composition, fixed physical and chemical properties

Mixture: A mixture is made up of a mixture of multiple substances (elemental substances or compounds)). The mixture does not have a chemical formula.

There is no fixed composition and properties, and each element or compound retains its original properties. In the mixture, a variety of substances contained in it do not react with each other and still maintain the original chemical properties.

The key to distinguishing whether it is a mixture or a pure substance is to see whether the substance can be written in a single chemical formula, such as water mixed with ice, the molecular formula is H2O, then it is pure; For example, hydrochloric acid is made by mixing H2O with HCl, so it is a mixture.

Containing only one molecule is a pure substance, such as water and sulfuric acid; Mixtures containing more than 2 molecules, such as air and flour.

Pure matter is composed of only one substance. A mixture is made up of two or more substances.

For example, air is composed of oxygen, nitrogen, etc., so it is a mixture; Brine is made up of salt and water, so it is a mixture. There is only one kind of oxygen, so it is pure; Carbon dioxide is a substance, so it is also pure.

Elemental substances are pure substances composed of the same elements.

Compound: A pure substance composed of two or more elements (as distinguished from elemental).

Mixture: A mixture is a substance that is formed by mixing two or more substances.

Purity: Purity refers to a polymer that consists of a single element or a chemical compound.

2. The nature is different.

Elemental: Elemental matter cannot undergo decomposition reaction.

Compounds: Compounds can undergo decomposition reactions.

Mixture: The mixture has no fixed properties, such as no fixed melting and boiling points.

Pure substance: Pure substance has fixed properties, such as certain fixed melting and boiling.

Pure matter is a substance composed of a substance, composed of a fixed, fixed physical and chemical properties of the substance, with a special chemical symbol, can be expressed by a chemical formula; A mixture is a substance that is made up of a mixture of two or more substances. There is no fixed chemical formula for mixtures, no fixed composition and properties.

Substances are divided into pure substances and mixtures. A substance that is made up of a single substance is called a pure substance. Purity includes both elemental and chemical compounds. A compound is a chemical reaction that is produced. A pure substance composed of two or more elements (as distinct from elemental matter).

First, the composition of matter is different

1.A mixture is a substance formed by mixing two or more substances. Mixtures have no fixed chemical formula, no solid composition and properties, and no chemical reaction occurs between the various components that make up the mixture, keeping them in their original properties.

Mixtures can be physically separated from the substances. It is not chemically synthesized.

2.Pure substance refers to a polymer composed of a single substance or a chemical compound, composed of a fixed, fixed physical and chemical properties, with a special chemical symbol, can be expressed by a chemical formula.

Second, the classification is different

1.Mixtures are classified into liquid mixtures, solid mixtures, and gas mixtures according to their form.

1) Liquid mixture. Among the subdivisions: turbidity, solution, colloid.

2) Solid mixtures. For example: steel, aluminum alloys.

3) Gas mixtures. For example: air.

2.Purities are divided into compounds and elementals.

1) Compounds: Pure substances containing different elements.

Such as: carbon dioxide, iron oxide, potassium permanganate.

2) Elemental: a pure substance composed of the same element.

Such as: hydrogen (H), nitrogen (N), oxygen (O).

Third, the characteristics are different

1.Pure substance: a substance with a fixed composition and fixed physical and chemical properties; There are specialized chemical symbols.

2.Mixture: Composed of more than two elements.

Pure matter is a substance composed of a substance, composed of a fixed, fixed physical and chemical properties of the substance, with a special chemical symbol, can be expressed by a chemical formula;

Example: O2N2

c、mg、fe、p2o5fe3

o4mgo、p、h2

o、h2so4

naoh、na2

CO3 Note: If a pure substance contains an isotope of an element (e.g. "water" has both H2O and D2O), then it is still pure.

First, the composition of the elements is different.

1. A mixture is composed of two or more substances.

2. Pure matter is composed of only one substance.

3. A compound is composed of two or more elements.

4. Elemental matter is an elemental composition.

Second, the nature is different.

1. Elemental matter cannot be decomposed by reaction.

2. Compounds can undergo decomposition reactions.

3. Pure matter is composed of the same substance, it has a certain composition, which can be expressed by a chemical formula, and pure matter has certain properties (such as fixed melting and boiling points).

4. The mixture is made up of a mixture of different substances, without a certain composition, and cannot be expressed by a chemical formula. The mixture does not have fixed properties, and each substance retains its original properties (e.g., there is no fixed melting and boiling point).

3. Different examples.

1. Elementality. Common gases are: hydrogen, oxygen, nitrogen, rare gases, etc.; Solids are: carbon, sulfur, phosphorus, iron, aluminum, copper, gold, silver, tungsten, manganese, magnesium, etc.

2. Compounds.

Such as ammonia NH3, methane CH4, phosphorus pentoxide P2O5, carbon disulfide CS2, etc.; Some compounds are composed of atoms, such as silicon dioxide SiO2, silicon carbide SiC, etc.

3. Pure substance.

Such as C, MG, FE, MGO, P, oxygen, nitrogen, potassium chlorate, etc.

4. Mixture.

Such as air containing oxygen (O2), nitrogen (N2), noble gases, carbon dioxide (CO2) and other gases and impurities; Petroleum (**), natural water, solutions, muddy water, milk, alloys, fossil fuels (coal, natural gas, oil), etc., containing various organic substances.

Substances include purities and mixtures:

There is only one chemical formula for the composition of pure matter, and only one substance such as CO2, H2O, Na, etc. are pure substances.

The mixture has a variety of substances, such as mineral water, seawater, solutions, etc., including compounds and elemental substances

A compound is a pure substance that contains two or more elements. For example, CO2, Na2SO4, HNO3, etc.

Elemental is a pure substance that contains one element. For example, Cl2, Au, Cu, I2, O2, etc.

Mixture is a general term that contains two or more different substances, and there is no reaction between substances, such as: air is composed of different substances such as oxygen, nitrogen, carbon dioxide, etc., which is a mixture. Pure substances refer to substances that contain only one substance, including both elemental and compound.

Elemental matter refers to a pure substance composed of the same element, such as: oxygen is a substance, it is a pure substance, and there is only one oxygen element; Compound refers to a pure substance composed of different elements, such as: sodium chloride is just a substance, it is a pure substance, and it is composed of two different elements: chlorine and sodium.

If a substance contains multiple components (containing multiple molecules, which cannot be expressed by one chemical formula), it is a mixture; If it contains an ingredient (containing a molecule, which can be expressed by a chemical formula), it is pure.

If there is only one element in a pure substance (e.g., hydrogen H2 contains only hydrogen element), it is elemental, and if it contains multiple elements (e.g., water H2O contains hydrogen and oxygen), it is a compound.

Pure matter is made up of a substance, like water, diamonds, gold. There are many mixtures, clouds, atmosphere, and so on.

Pure: A substance composed of a single substance. Purity can be expressed in a single molecular formula. For example, water (H2O).

Mixture: A substance formed by mixing two or more substances. For example, table salt solutions.

Compounds: Pure substances composed of different elements. For example, sulfuric acid (H2SO4).

C12 (carbon-12).

Compound: A pure substance composed of atoms of two or more elements, which must be a pure substance and should not be avoided. For example, copper sulfate (normal salt), sodium hydroxide (alkali).

Sulfuric acid (acid) oxide: a compound composed of two elements, one of which is oxygen. (Do not be compounds).

For example, sodium oxide (basic oxide).

Mixture: A mixture is a mixture of two or more pure substances, as opposed to a pure substance.

Mixtures, such as bronze, are made up of substances such as copper and tin-lead.

Pure: A substance composed of a single substance.

It can be a simple substance, or it can be a compound, as long as it is the same substance. For example, carbon, sodium sulfate.

Purity. It refers to a substance composed of a single substance or a chemical compound, with a fixed composition and fixed physical properties.

and chemical properties of substances, which have special chemical symbols and can be represented by a chemical formula. A mixture is a substance that is made up of a mixture of two or more substances. There is no fixed chemical formula for the mixture, no fixed composition and properties, and no chemical reaction occurs between the various components that make up the mixture.

will keep them in their original nature. Mixtures can be physically separated from the substances. It is not chemically synthesized.

A compound is a pure substance (as distinguished from an elemental) consisting of two or more different elements. A compound has certain properties, both from the elements or ions it contains, and from other compounds, and often with a certain composition.

In addition to pure substances, carbon dioxide is a mixture, for example, carbon dioxide is a pure substance, but seawater, there are many substances in it, such as water, sodium chloride, etc., which is a mixture. Pure substances include compounds, which are made up of one element, such as oxygen, and compounds, which are made up of multiple elements, such as carbon dioxide.

If it is a substance, the compound must be pure, and the pure substance is not necessarily a compound, but can also be elemental.

The same substance (elemental) is composed of two or more different elements, which are all compounds, which must be produced by certain chemical reactions. An element is called elemental.

Mixtures are not necessarily, such as diamond and graphite, which are composed of one element, but together they are mixtures, and they are definitely not compounds.

Purity and mixture are macroscopic and distinguish one or more substances.

Elemental and compound are at the level of the elements, the distinction between one element and multiple elements.

Compounds must be pure, and pure substances include many things, such as organic and inorganic substances; Inorganic matter includes elemental matter and compounds, elemental matter is composed of only one element, but compound is composed of two or more elements.

In addition, a substance composed of only one element is not necessarily pure, this is a trap problem, such as a mixture of O2 and O3, there is only one element, but there are two elemental components, which is a mixture.

compounds and.

Elemental substances are pure. A substance made up of one element is:

Elemental, more than two elements are.

Compound. But the premise is a substance.

Sometimes one element can make up two substances, and these two substances are mixtures. Such as oxygen and ozone.

Pure substances are divided into elemental and compound.

Elemental substances are pure substances composed of the same elements.

A compound is a pure substance composed of two or more elements, and a pure substance formed by the same atom must be elemental, and must not be a compound.

Both deuterium and tritium belong to the hydrogen element. HD is a pure substance composed of the same elements, so it is not a compound.

Compounds are a category of pure substances, so when it comes to compounds, they must be pure substances, but pure substances also include elemental substances, so pure substances are not necessarily compounds.

As long as it is composed of two or more different elements, it is a chemical compound.