How to balance the chemical equation in the first year of high school

1. For those relatively simple chemical equations for balancing, the best way to use is the least common multiple methodFor example: mg+o2 ignition = mgo, the number of oxygen atoms on the left is 2, and the number of oxygen atoms on the right is 1, then the least common multiple of 2 and 1 is 2, then the coefficient in front of the magnesium oxide on the right should be 2, the coefficient in front of the magnesium oxide has become 2, then the coefficient in front of the magnesium atom should also be 2, the final formula should be 2mg+o2=2mgo, of course, the final must indicate the conditions for the chemical reaction, For example, magnesium reacts with oxygen to form magnesium oxide, and the condition required is to ignite oxygen, and finally the correct chemical formula can be obtained: 2mg+O2 ignition ==2mgo

2. For those more complex chemical equations, we can choose to observe the trim method to trim the chemical formulaFor example, the chemical reaction between water and iron, high school students should know that if water and iron react, they will form a very complex chemical formulaFerric tetroxide,Then we can find out the coefficients required for each element from the chemical formula of this complex ferric tetroxide, there are 4 oxygen in ferric tetroxide, then the ** of oxygen is water (h2o), then the coefficient in front of water should be 4, and there are three iron elements in ferric tetroxide, and the iron in ferric tetroxide ** is more than elemental iron, then the coefficient in front of the iron element should be 3, and finally the chemical equation is obtained by adding three iron elements and 4 water to form an iron tetroxide and a hydrogen, Later, it is indicated that the state of hydrogen is a gas, and it is enough to mark it with an ascending symbol.

Finally, I would like to say that if students want to accurately assign the coefficients in a chemical formula, they should indeed find the right way to do itIt makes the distribution coefficient faster and can shorten the solution time in the problem solving, but it also requires students to carefully study the chemical equation and carefully observe the experiment that the teacher does for you, so that you can figure out the generation conditions of the chemical equation and what is the state of the molecule after the generation, otherwise you only learn to allocate the coefficients in the chemical equation, but you don't know whether the formation is a gas or a solid liquid, and there is no way to accurately write the generation conditions, and there is no way to score?

Balance can be carried out by the least common multiple method and the observation method; It is necessary to memorize the valency of each element, and you can also match it according to the conservation of elevation, charge and element, and practice more.

The least common multiple method can be utilized. Observe each element, but also pay attention to the change in quantity, so that you can quickly trim. It is also possible to trim according to the chemical valence.

Understand the chemistry between the parts, keeping in mind the change in valency; To do more experiments, you can use the observation method, the least common multiple method, the undetermined coefficient method, and the odd and even matching method.

The best way is to write more and memorize, practice makes perfect. Unfamiliar equations can be solved by solving equations to solve the balance,

High school chemistry equation balancing methods and techniques are as follows:

1. Least common multiple method.

Applicable conditions: The matching atom appears only once on the left and right sides of the equation, and this method is suitable for common chemical equations with little difficulty.

2. Odd spouse law.

Applicable conditions: It is applicable to the multiple occurrences of an element on both sides of the chemical equation, and the total number of atoms of the element on both sides is odd and even.

3. Establish a law.

Applicable conditions: such as the reaction of most hydrocarbons or compounds containing hydrocarbon and oxygen with oxygen, as well as certain decomposition reactions.

Fourth, the fraction balancing method.

This method can balance chemical reactions with elemental participation in the reaction or elemental generation. Specific steps:

1) first trim the atoms of each element in the compound;

2) equalize the atoms of elemental elements with fractions;

3) Remove the denominator so that the stoichiometric number after trim is an integer.

5. Algebraic method (also known as the method of undetermined coefficients).

Applicable conditions: There are many types of reactants or products, and the trim does not know where to start with the more complex reactions.

6. Observation balancing.

Applicable conditions: Sometimes there will be a substance with a complex chemical formula in the equation, and we can use this complex molecule to deduce the coefficients of other chemical formulas.

There is a law for balancing, but there is no definite law. For the same reaction equation, different methods may be used to balance, and sometimes even several methods may be used at the same time.

High School Chemistry Equation Trim Methods and Skills:

1) Least common multiple method:

In the balancing chemical equation, the elements with a more complex "number" are observed before and after the reaction, and the balancing is carried out first.

First, calculate the least common multiple of the atoms of the element before and after the reaction, use the method of filling in the stoichiometric number before the chemical formula, balance the atom, and then observe the number of atoms of other elements, so that the types of elements and the number of atoms of reactants and products in the chemical reaction are equal.

2) Observational Method:

A method for judging the stoichiometric number of a substance by analyzing the chemical formula of a substance.

3) Odd to even method:

The method of selecting an element with an odd and even number of atoms in the chemical formula before and after the reaction as the starting point of balancing, turning the odd number into an even number, and then leveling the atoms of other elements is called the odd to even method.

4) Normalization method:

Find the key chemical formula in the chemical equation, set the number before the chemical formula as 1, and then balance the number before the other chemical formulas according to the key chemical formula.

If the measured number is a fraction, and then the measured number is multiplied by the same integer, and the fraction is turned into an integer, this balancing method in which the key chemical formula measurement number is 1 is predetermined, which is called the normalization method.

Trim Tricks for Chemical Equations:

1) Master the essentials of writing chemical formulas:

In the series of chemical terms, the chemical formula is in the position of connecting the previous and the next, and there are element symbols and valency knowledge before it, which is the basis for writing chemical formulas; Then there are chemical equations and ionization equations, etc., which are based on chemical formulas, and if there is an error in the chemical formula, the whole formula is meaningless.

If we use such an erroneous chemical equation as the basis for chemical calculations, we will be even further wrong, and it can really be described as "a small miss, a thousand miles". It can be seen that mastering the essentials of writing chemical formulas directly affects the learning of other chemical terms and other chemical knowledge and skills.

2) Master the skills of writing chemical equations:

In short, when writing chemical equations, they must conform to the objective laws of chemical reactions and cannot be fabricated out of thin air. The writing procedure is generally as follows: write the chemical formula - the coefficient should be balanced - the middle and equal signs - the conditions should be noted - the gas or precipitation should be generated, which should be marked with the arrow number.

To write chemical equations well, it is also necessary to master and use the solubility table of acids, bases, and salts, the order of metal activity and the valency of common elements and atomic groups, as well as the skills of writing chemical formulas of substances.