**Nguyen Thi Bich Hien** - Faculty of Chemistry, Vinh University, Vinh city, Nghe An Province, Vietnam.

**Bùi Thị Hiền** - Nguyen Van Cu High school, Hoc Mon District, Ho Chi Minh City, Vietnam.

*Abstract:* Search mechanism solve the chemical problem to help students not only the skills to solve problems better, but also to better understand the nature of the exercises, and more importantly, the development of thinking and formed their ability to solve their problems. So to help students better understand how to find the mechanism allows the chemical problem we have made the process of research to find mechanisms to solve the problem allows students to apply the learning.

*Keywords:* Mechanism for solving the problem, chemistry problem, development thinking, problem-solving capacity.

1. Introduction

Construction mechanism allows the problem is a very important stage, it is crucial to solve the problem successfully or unsuccessfully, and it contributed significantly in training and development from thinking, problem-solving capabilities for students. Usually, when solving a problem, the solution is often the problem with existing knowledge of their experience, often find signs to the problem of a familiar problem as previously. This operation fact is only part of the operation mechanism allows processes to find the problem, if so will give students a habit of dependence, depression, mental confusion or bewilderment as having a problem completely new compared to other types of problems encountered previously and operations will not solve the problem gives students the joy, the passion for learning. Practice has proved, through the search mechanism that allows the problems of the new understanding of the corners of the problem, to better understand the process of thinking, the mindset manipulation should be mobilized, the tools needed to solve the problem, identify the key knowledge will be achieved through problem solving, understand the hidden facts, to place misleading.

On that basis, to assess the problem, discovered a number of problems, mistakes, some mistakes can be acquired in the course of solving the problem. Since it will be formed for students seeking to solve the problem in a scientific way without groping or based on familiar situations and more importantly, the student will develop thinking, formation and development of the methods of problem in learning and in life.

2. Construction processes to find mechanism allows the problem

a. The nature of the problem allows mechanism

According to Nguyen Ngoc Quang authors “permission mechanism of solving the problem, in fact the original problem transforms into a continuous series of intermediate problems more elementary, more basic, until overcome contradiction between the conditions and requirements of the problem”[5].

Search mechanism is essentially the problem to try to correct the nonconformity or contradiction between the conditions and requirements of the problem, change them to finally bring them to unity. Typically, the data of the problem are not immediately required to meet the problem, in other words, the facts were not enough to force the problem solver must find ways to transform a set of conditions, find the new data, along with the solution it must also change the requirements until the facts get more and more requests to find and interact with each other to find a match, the transformation process will stop. This is also the time to find out how to solve the problem, the contradiction between the data and requirements of the problem and is no longer at the end of the search mechanism allows solving the problem. In fact, this process is not easy for the people that it is actually a path seeking ways to solve complex problems, the way it's looking for are not available, sometimes successfully and sometimes failure forced to find another way [3]. D.Polya wrote about this period as follows: "This period is often long and winding, the concept of the program may be formed gradually or after the time trial is unlikely to have results and the lingering doubts, it may appear like a bolt of lightning ..." [5]. It is in this process of change the succession to the system posed questions to find out additional facts and asks for more. Specifically, during the requested change poses the question: to find the needed requirements to the facts, the facts given will be followed by the new requirements are modified. similar to the variation of the data, we ask the question: is this fact means nothing, it is equivalent to any facts? The answer to that question will be the data can be modified or call the hidden facts of the problem. On the other hand, in the process of change problem we are always looking for additional requirements for interaction with the data or initial data were transformed our view of the problem is appropriate, to satisfactorily determine orientation change subsequent to the problem. Thus, the focus here is the nature of the problem changes by modifying the data and requirements.

b. Construction mechanism allows processes to find the problem

On the basis of the nature of the mechanism allows the problem, we have built the process logs algorit mechanism allows the problem as follows:

Step 1: Change requests

Step 2: Change request has been interacting with the data of the problem has to. If the response is (or is appropriate), then come to a conclusion on how to solve the problem. If they do not match, the switch continues to step 3.

Step 3: Continue to find more change requests in the previous step and interact with data to find, if not satisfied, then we continue to change and test the interaction between them until it stopped satisfy again.

Indeed in step 2 and step 3 has created a structural loop operation.

c. Preparation of algorit grap mechanism allows the problem

If algorit of the mechanism allows the problem to point out the steps to take to find a mechanism allowing the grap solve algorit mechanism of solving the problem is visual diagram describing the steps should have been done to find out the encoding mechanism allows the problem.

On the basis of the mechanism allows the construction algorit solve the problem, we can easily solve the problem set is algorit against algorit by finding mechanisms solve the problem. This time we will be compiling the process steps, at each step of the transformation made to go to the answer. It is algorit of the program.

Grab the algorit solve the problem and sticking together organically, grap is the objective basis for determining its corresponding algorit. Moreover grap also allows us to calculate the level of complexity and difficulty of the program a given problem, based on the structure of grap.

d. For example

Mix well 10g mixed metals (Zn, Fe) in HCl solution excess out 2.24 liters H2 gas (TOR). Drying the reaction solution obtained after how many grams of anhydrous salt?

Applying the processes of problem resolution mechanism has been built on we will analyze the problem and change the following mechanism to find it:

The first way: To calculate the mass of anhydrous salt form we change this requirement by passing the requirements of the problem to find mass of the metal and mass of Cl-. Compared with the information of the chemical problem, we know the mass of metal, now just need to find the mass of Cl-; Similarly to calculate the mass of Cl-is making this request to: calculate mass of HCl was involved reactions. Requirements interact with the information of the chemical problem that can not be met immediately, again transform this requirement into calculated mass (moles) H2 formed. This requirement can be satisfy, as was proposed for moles H2 formed through the volume of H2 gas escape is 2.24 liters. As we end the program solve the problem. The crux of the matter is that we have to look good to realize that the mass of salt is also the mass of the ions created it.

The second way: apply the law of conservation of mass, the total mass of the substance in the reaction by the total mass of the resultant reaction: To calculate the mass anhydrous us to change this requirement to: calculated total mass of the product and mass of gas H2 exhale in the equation of chemical reaction other. Compared with the infomation of the problem is a request that was met by mass hydrogen gas escaping hydrogen gas volume is 2.24 liters. As a requirement is can not satisfy that amount of product formed, and compare them with existing knowledge of the notice of the mass formed by the total mass of the substances involved. Requirements of the chemical problem has been transformed into: the mass of the metal and participated HCl reaction; continue to interact with the information they need to find the volume of HCl was also involved mass the metal hypothesis has to be 10 grams. So to calculate the volume of HCl to change the mass of H2 gas formed between metals react with HCl solution. This time the search mechanism allows the problem ended.

It is clear that, based on the algorit grap mechanism that allows the chemical problems of students could understand why the solution to find, understand the nature of what is allowed, through the algorit grap mechanism allows solution also allows us to find a solution that is more concise, more optimized so that the decision to choose the method of short, smarter. At the same time be able to figure out all the steps presented by reversing mechanism allows the algorit of the recently found. On the other hand, in the process of searching mechanism allowing the students to solve conducted a series of operations thinking, given the hypothesis and the direction of finding solutions to problems, and perform the test program math activities by comparing the information change, find more information to the requirements of the chemical problem posed. This operation is repeated until the change of information in accordance with the requirements of chemical problem. The process has the capability of students to action-oriented, problem-solving ability in learning.

3. CONCLUSION

Thus, the requirements and guidance mechanism enables students to solve the problem through the construction process mechanism allows solving the problem proposed above, students not only have better problem-solving skills, but also understand better the nature of the problem so that you understand what to do for my students to approach a problem. There is so effective new teaching chemistry are more advanced, the use of exercise not stopped on strengthening the knowledge, skills, forging, developing higher thinking is a guide for students find a solution, how to solve the problem so that the capability of solving problems in school and in life. This is the most important goal to be achieved in education.

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