What is the cross method in chemistry and what is the chemical cross method?

The criss-cross method, if understood thoroughly, is actually not difficult.

The criss-cross method is an easy way to calculate the average amount and composition of a two-component mixture. Problems that can be calculated as m1n1 m2n2 m (n2 n2) can be calculated according to the cross method.

where m represents an average amount of the mixture, and m1 and m2 represent the corresponding amounts of the two components. For example, M represents the average relative molecular mass, M1 and M2 represent the relative molecular mass of the two components, N1 and N2 represent the share of the two components in the mixture, N1: N2 represents the ratio of the quantity of the two components of the substance in most cases, and sometimes it can also be the ratio of the mass of the two components

n2 denotes the ratio of the amount of a substance of the two components; For example, the mass fraction, and the mass percentage of the element, then n1:n2 represents the mass ratio of the two components.

Precautions for using the criss-cross method:

1. When using the cross method, it is necessary to distinguish whether the ratio obtained is the ratio of the quantity of the substance or the ratio of the mass. When the unit attribute value has the quantity factor of the substance, the ratio obtained by the cross method is the ratio of the quantity of the substance; When the value of the unit fraction attribute has a mass factor (such as the calculation of the mass fraction of the solution, etc.), the ratio obtained by the cross method is the mass ratio.

2. The cross method is mainly suitable for choice and fill-in-the-blank questions, and is generally not used in large calculation problems, because it is difficult to describe clearly with limited words in the writing process, so the conventional method is generally used in large calculation problems.

The criss-cross method, if understood thoroughly, is actually not difficult.

The chemical cross method isAn easy way to calculate the average amount and composition of the mixture between the two groups. Any problem that can be calculated by multiplying m1 by n1 plus m2 by n2 equals m times n can be calculated according to the cross method. m represents the average amount of a mixture, and m1 and m2 represent the corresponding amounts of the two components.

For example, m represents the average relative molecular mass, m1 and m2 represent the respective relative molecular mass of the two components, n1 and n2 represent the share of the two components in the mixture, and n1 vs. n2 in most cases represent the ratio of the quantities of the two components.

Sometimes it can also be the ratio of the mass of two components, and the key to judging is what physical quantity N1 and N2 represent in the mixture, such as the amount of matter, the quantity fraction of matter, the volume fraction, etc.

How to learn chemistry well

Chemical reactions include reduction reactions, oxidation reactions, chemical reactions, decomposition reactions, acid-base neutralization reactions, etc. In chemical reactions, we must firmly grasp the change of valency, and knowing this, I believe that it is not difficult to react.

Practice is the only criterion for testing truth, so experiments also account for a considerable weight. You need to know how to use some experimental equipment, such as condenser tubes, test tubes, iron frames, alcohol, etc.

In addition, when doing experiments, be sure to pay attention to your own safety and seize the class. In class, the teacher will often talk about the difficult points that are easy to mix, and you must do a good job of preparation before the teacher speaks. Connect with life.

Chemistry is closely related to our lives, so we have to connect with the actual life of the moment?

The criss-cross method, if understood thoroughly, is actually not difficult.

It is an easy way to calculate the average amount and composition of the mixture between the two groups. All problems that can be calculated according to m1·n1+m2·n2=m·n can be calculated according to the cross method.

where m is the average amount of a mixture, and m1 m2 is the amount of the two components. For example, m represents the average relative molecular mass, m1 m2 represents the relative molecular mass of the two components, n1 n2 represents the share of the two components in the mixture, and n1:n2 in most cases indicates the ratio of the amount of the two components of the substance, and sometimes it can also be the ratio of the mass of the two components.

The key to judging is n1, n2 represents the share of physical quantities in the mixture, such as the amount of matter, the quantity fraction of matter, and the volume fraction, then n1:n2 represents the ratio of the quantity of the two components of the substance; For example, the mass fraction, and the mass percentage of the element, then n1:n2 represents the mass ratio of the two components.

Comparative law. We often say that the cross method is actually the cross comparison method, which is a graphical method. The cross diagram method is actually a simple algorithm instead of the summation formula, which is particularly suitable for the calculation of mixtures of two total quantities and two relationships (i.e., the calculation of 2-2 type mixtures), which is used to calculate the ratio of the two components in the mixture.

This kind of problem is actually similar to the "chicken and rabbit in the same cage" problem, so the first thing that should be done to solve this kind of problem is to "one-sided". That is, if it is just one of the substances, what is the situation? After that, you can compare by making a difference.

The percentage concentrations of solutions A and B of the same substance are a%, b% (a%>b%), respectively, and the solution with a percentage concentration of c% is now prepared with these two solutions. Q: What should be the mass ratio of these two solutions?

The solution of the same substance, the mass of the solute before and after preparation is equal, and this principle can be used to solve the solution.

Set M1 and M2 grams of the two solutions A and B respectively, and the mass of the solution after mixing the two solutions is (m1+m2). Columnar.

m1a%+m2b%=(m1+m2)c%This formula is sorted out: m1:m2=(c-b) (a-c), m1:m2 is the mass ratio of the two solutions A and B.

a/b=(c-b)/(a-c)①

If we take the solute contained in 100g of solution as a benchmark, the above equation expresses the ratio of their mass to the mass fraction ratio of the solution when mixed.

The following cross-cross forms are available. ac-bc

It can be seen from the comparison of BA-C and the two equations: in the cross relationship, (C-B) (A-C) is the mass ratio of component A and component B when mixed, and is extended to the two-component mixed system, when the mixed system with a certain side plum mass is used as the benchmark to obtain the cross relationship, the ratio is the mass ratio (for example, the mass fraction is based on the mass); If the chemical significance of the ratio of c-b to a-c is determined by the mean c, then the ratio is the ratio of the amount of c-b in component a and a-c in component b. If c is the mass or mass fraction, then (c-b) (a-c) is the ratio of the mass of the solution of component A and component B; If c is the density, then (c-b) (a-c) is the ratio of the volume of the solution of component a and component b; If c is the molar mass, then (c-b) (a-c) is the ratio of the amount of the substance of component A to component B.

In this case, the content of each component in the mixture can be found using the cross method.

2. The criss-cross method can be used to calculate the concentration of the solution, such as the dilution, concentration or mixing of the solution. Use this method to make the problem solving process simple, fast and correct. The following is an example of how to explain the principle of the cross method.