How to determine the nature of the oxide

A chemical compound consisting of oxygen and any other element of the periodic system, are called oxides. Depending on the properties of their klassificeret of basic, amphoteric and acidic. Nature of oxides it is possible to determine theoretically and in a practical way.

You will need

• - periodic system;
• - laboratory glassware;
• - chemical reagents.

Instruction

1. You need a good understanding of how the properties of chemical elements depending on their location in the table of D. I. Mendeleev. So repeat the periodic law, electronic structure of atoms (it depends on the degree of oxidation of elements) and so on.
2. Without action, you will be able to establish the nature of the oxide, using only the periodic system. It is known that in the periods from left to right alkaline properties of amphoteric oxides are replaced on, and then on acid. For example, in the third period, sodium oxide (Na2O) shows the basic properties, the compound of aluminium and oxygen (Al2O3) is amphoteric, oxidized lignite through extraction of chlorine (ClO2) is acidic.
3. Keep in mind, the main subgroups of the alkaline properties of the oxides are enhanced from top to bottom, and the acidity is on the contrary weakened. So, in I know oxide of cesium (CsO) basicity stronger than that of lithium oxide (LiO). In group V oxide of nitrogen (III) acid, and the bismuth oxide (Bi2O5) is already basically.
4. Another way of defining the nature of the oxides. For example, given the task to prove empirically the basic, amphoteric and acidic properties of calcium oxide (CaO), oxide 5-valent phosphorus (P2O5(V)) and zinc oxide (ZnO).
5. First, take two clean test tubes. Of bottles, with the chemical spatula, pour in a little one CaO, and P2O5 in the other. Then pour in both of the reagent in 5-10 ml of distilled water. Stir with a glass rod until complete dissolution of the powder. Dip pieces of litmus paper in both test tubes. Where is calcium oxide indicator turns blue, which is a proof of the basic nature of this connection. In the vial with oxide of phosphorus (V) the paper will turn red, therefore, P2O5 is acidic oxide.
6. As zinc oxide is not soluble in water, for evidence of his being appeared perform reactions with acid and hydroxide. In either case, the ZnO crystals will enter into a chemical reaction. For example:
   ZnO + 2KOH = K2ZnO2 + H2O
   3ZnO + 2H3PO4→ Zn3(PO4)2↓ + 3H2O