New chemistry research programs aim to achieve an organic unity of student learning and development. The task of the teacher is not only to equip schoolchildren with knowledge and practical skills but also mental operations. And the student’s task is to arm himself, respectively.
One of the most important mental operations by which knowledge is acquired is comparison. Logically, the comparison is presented as the basis of generalization, on the one hand, and as the unity of such logical operations as analysis and synthesis, on the other. But in order to form a comparison as a method of their mental activity, it is necessary to use comparison as a method of training. The use of comparison as a didactic technique is an indispensable condition for the formation of analytical and synthetic activity. Students get the task of writing an essay specifically for this purpose.
Among the thinking methods of studying chemistry, an important place is taken by comparison. The comparison process activates cognitive activity, develops abstract thinking, conscious and lasting assimilation of knowledge. This technique consists of comparing when features are distinguished by which the comparison is made, and contrast, which establishes the similarity and difference between objects.
Objects or phenomena can be compared according to one or more grounds. In the process of comparison, students study not only external signs, but also properties. A comparison helps to track objects and phenomena in change and development.
Comparing objects and phenomena with each other, students identify private and general, essential and non-essential features. A generalization is based on the identification of common and essential features. It is this that leads to the formation of concepts, to the knowledge of regular relationships and relationships.
The comparison makes it possible to identify new aspects of objects, their relationships, such features of objects and phenomena that are not perceived when studied separately. In the process of comparison, students penetrate into the essence of objects, without outside help they notice properties that are imperceptible at first glance, comprehend the features of phenomena.
As you already understood, we will compare the general and distinctive features of two chemical elements, phenomena or reactions. Therefore, we need to develop an action plan that can be arranged in a table.
Depending on the assignment, the student makes a conclusion on the basis of incomplete or complete comparison or the most significant signs by which the studied objects are compared and contrasted.
You can go further in your work and work to compare and contrast the signs of chemical substances or phenomena in a deeper way according to the following table.
For example, according to this table, you can find several similar and different physical properties of aluminum and copper, due to which these metals find the same application.
The subject chemistry provides rich and diverse material for comparison. We list those concepts and topics while studying, you can write a comparison and contrast essay:
The above concepts and topics show that comparisons can be made within one topic or section, between different topics or sections, between courses of inorganic and organic chemistry.
In order to correctly highlight all the necessary features, we need to write down the molecular and structural formulas of aniline and answer the question: what derivative is aniline from and what class of substances does it belong to?
It is possible to separate two components in the aniline molecule – the benzene ring and the amino group. This makes it possible to consider aniline as a derivative of benzene and ammonia and to establish that it is representative of a new class of compounds – aromatic amines.
The chemical structure of aniline allows you to compare it with the limiting amines and phenol. This comparison leads to two problems: why does aniline exhibit weaker basic properties than limiting amines, and why, in contrast to benzene, does aniline interact with bromine water under ordinary conditions?
Students already know what role hydrocarbon radicals play in enhancing the basic properties of saturated amines compared to ammonia. They are also aware of the role of the phenyl radical, which determines the weak acid properties of phenol. Comparing these two facts, first among themselves, and then in relation to the aniline molecule, students come to the conclusion that aniline, due to the influence of the phenyl radical, exhibits weaker basic properties than limiting amines.
Students establish the reason for the increased reactivity of the benzene ring in aniline by comparing it with phenol. Thus, it is possible to conclude that the amino group in the aniline molecule (like the hydroxyl group in the phenol molecule) affects the benzene core, thereby causing the substitution of hydrogen atoms under normal conditions.
When comparing objects, the following requirements must be observed:
The success of an essay depends largely on whether students have the ability to identify what is similar and different. They definitely need to learn to notice the similarities where the phenomena on the outside are very different from each other and to find a difference in those cases when the external similarity is bright.
It is a paradox that students often cannot change the way they act when completing assignments and do everything according to the template, but at the same time, they don’t apply the learned actions where necessary, because they do not know how to establish similarities.
This explains a significant part of the mistakes made in the study of chemistry and writing an essay. For example, it is difficult for students to describe the similarities and differences between neutralization reactions during the interaction of soluble and insoluble bases with acids from the point of view of the theory of electrolytic dissociation, asserting that there is no difference between them, since in both cases the essence of the reactions is to form a weakly dissociating substance – water. However, making equations of such reactions in the abbreviated ionic form helps them to establish both similarity and difference.
How to prevent such errors? How can they be eliminated if they are already approved? Practice shows that the opposite phenomena are most easily distinguished. Psychological studies prove that the contrast of concepts and rules that are different in content protects them from further confusion.
Therefore, when you need to contrast two phenomena, you can act in various ways. In the first case, two concepts (or rules) are submitted for comparison at the same time. In the second, at first one concept is studied, and then after its firm assimilation, the second is introduced as a contrast to the first. However, there is still the possibility, after sufficiently good assimilation of both concepts, to carry out their comparison.