Contextualization

Chemistry is a science that studies the properties and behaviors of elements and substances, as well as the transformations that occur with them. Within this study, the distinction between physical and chemical phenomena is fundamental.

A physical phenomenon occurs when the substance changes its form, but not its composition. A classic example is the change in the physical state of water, which can change from the solid state (ice) to the liquid state (water) and to the gaseous state (vapor), without changing its composition, which remains H2O.

A chemical phenomenon, also called a chemical reaction, occurs when there is a change in the composition of the substance, generating new substances. An example is the combustion (burning) of paper, which generates ashes and various gases, with different compositions from the original.

Physical and chemical phenomena are present in our daily lives, in food cooking processes, in the production of medicines, in the functioning of electronic devices, in the decomposition of organic waste, among other examples. They are essential for life and technology.

Understanding these phenomena is fundamental to understanding Chemistry and its practical applications. This understanding allows us, for example, to choose the best way to store a food, whether it should be refrigerated or frozen, or whether it can be kept at room temperature. It also allows us to understand why some materials degrade when exposed to the sun or to certain substances.

To delve deeper into the subject, we suggest the following reliable sources:

1. Book "Chemistry: The Central Science", by Brown, LeMay, Bursten, Murphy and Woodward.
2. Chemistry Portal (https://www.portaldaindustria.com.br/senai/canais/ola-quimica/fundamentos-da-quimica/fenomenos-fisicos-e-quimicos/)
3. YouTube Channel "Chemistry in Action", by Professor Paulo Valim.

Practical Activity

Activity Title: "Spotting Changes: Physical and Chemical Phenomena"

Project Objective:

The main objective of this project is to identify and differentiate between physical and chemical phenomena by conducting practical experiments, analyzing and discussing the results.

Detailed Project Description:

Students will be divided into groups of 3 to 5 members. Each group will be responsible for conducting three experiments, each of which should demonstrate one example of a physical phenomenon and two of chemical phenomena. Finally, the groups must prepare a complete report on the experiments.

Materials Required:

1. Water and ice
2. Table salt
3. Vinegar
4. Baking soda
5. Glass or plastic cups (3 for each group)
6. Spoon
7. Stove or Bunsen burner (for teachers or students who are authorized to use it)
8. Scale to measure the mass of the materials before and after the experiments

Detailed Step-by-Step to Carry Out the Activity:

Experiment 1: Physical Phenomenon - Change of Physical State

1. Put ice in a glass.
2. Heat the ice until it turns into water and then into steam. (Procedure to be performed under the supervision of the teacher)
3. Note the observations on the change in the physical state of the substance.

Experiment 2: Chemical Phenomenon - Neutralization Reaction

1. Add a spoonful of baking soda to a glass.
2. Add vinegar slowly and observe the reaction that occurs.
3. Note the observations relevant to the reaction.

Experiment 3: Chemical Phenomenon - Dissolution and Crystallization

1. Add water to a glass.
2. Add table salt until it no longer dissolves, creating a saturated solution.
3. Heat the solution until all the salt dissolves and let it cool slowly.
4. Observe the formation of salt crystals in the glass as the solution cools.
5. Note the observations relevant to the reaction.

Project Duration: The project should be completed in one week, with the project execution time, considering the three experiments, being around two to four hours per student.

Project Deliveries:

After conducting the experiments, each group should prepare a written report containing:

1. Introduction: Contextualization of the project, presentation of the theme and its relevance in everyday life, as well as the project objectives.

2. Development: Description of the experiments performed, materials used, procedures adopted, presentation and discussion of the results. Also include the distinction between physical and chemical phenomena.

3. Conclusion: Conclusions drawn about the experiments, lessons learned, and the relevance of the distinction between physical and chemical phenomena.

4. Bibliography: Bibliographic references and other types of resources used in the project.

The report should be written in a clear and cohesive manner, presenting all the requested information in a detailed and organized way. Each section should complement the other, forming a document that correlates practice and theory.