The main subject of study in chemistry are the reactions between different chemical elements and substances.
Deep understanding of the patterns of interactionSubstances and processes in chemical reactions makes it possible to control them and use them for their own purposes. A chemical equation is a way of expressing a chemical reaction, in which formulas of initial substances and products are recorded, coefficients that indicate the number of molecules of each substance.
Chemical reactions are divided into reactions of compound, substitution, decomposition and exchange.
Also among them can be distinguished oxidation-reduction, ionic, reversible and irreversible, exogenous, etc.
Determine what substances interact with each other.Friend in your reaction. Write them on the left side of the equation. For example, consider a chemical reaction between aluminum and sulfuric acid. Place the reagents on the left: Al + H2SO4
Then put the sign "equal", as in the mathematical equation. In chemistry, you can find an arrow pointing to the right, or two oppositely directed arrows, a "sign of reversibility".
As a result of the interaction of metal with acid, salt and hydrogen are formed. Write reaction products after the equal sign, on the right.
Al + H2SO4 = Al2 (SO4) 3 + H2
The reaction scheme was obtained.
To make up the chemical equation, youIt is necessary to find the coefficients. In the left part of the previously obtained scheme, sulfuric acid includes hydrogen, sulfur and oxygen atoms in the ratio 2: 1: 4, on the right side contains 3 sulfur atoms and 12 oxygen atoms in the salt and 2 hydrogen atoms in the H2 molecule. On the left side, the ratio of these three elements is 2: 3: 12.
To equalize the number of sulfur and oxygen atomsIn the composition of aluminum sulfate (III), put the coefficient 3 on the left side of the equation before the acid. Now there are six hydrogen atoms on the left side. To equalize the number of hydrogen elements, put the coefficient 3 in front of it on the right side. Now the ratio of atoms in both parts is 2: 1: 6.
It remains to equalize the amount of aluminum. Since the salt contains two metal atoms, put a factor of 2 in front of the aluminum on the left side of the circuit.
As a result, you get the reaction equation of this circuit.
2Al + 3H2SO4 = Al2 (SO4) 3 + 3H2