What is a substance?
pure substances are elements and compounds
The word substance (a physical material) originates from Latin substantia, literally meaning "standing under". The word was used to translate the Greek philosophical term ousia.
It is a material that can undergo various transformations related to artificial or natural phenomena. The term substance specifically applies to a physical material with a definite chemical composition, that cannot be separated into constituent materials by physical means. The term "pure substance" may be used to indicate this. A substance may be an element or compound. Mixtures and solutions are combinations of one or more distinct substances.
A substance (pure substance) may exist as either a solid, liquid, or gas.
Matter of definite composition and properties.
For example, every pure element is a different substance. Every pure compound is a different substance.
Salt water is a mixture of two substances - sodium chloride and water. Its composition and therefore its properties are not fixed.
Gasoline is a mixture of hydrocarbons and (depending on the composition), gasoline's properties can vary.
The volume and mass of a substance are independent of the substance itself, but depend upon how much there is of the substance The density of a substance is the relation between how much volume you have of a substance and how much mass that volume has (and vice-versa). It is independent of how much there is of the substance and is thus a characteristic of the substance.
You find the number of atoms from the number of grams of a given substance by: Find the Moles of the Substance by multiplying the grams of the substance by the molar mass of the substance. ( Molar mass equals mass of substance per 1 mole of substance.) Grams x Molar Mass of Substance = Moles of Substance Take the moles of the substance and multiply it by Avogadro's Number (the number of atoms in…