Contextualization
Life as we know it depends on a multitude of processes that occur around us, many of which involve changes in the state of matter. The water cycle, which allows life on Earth, is a direct example of these changes. When water evaporates from the oceans, lakes, and rivers, it forms clouds in the sky. This water can then condense and fall to the earth as rain or snow, depending on the temperature. If the temperature is low enough, the water can freeze and become solid. This is an example of the three states of matter: liquid, gas, and solid.
State changes are physical transformations, that is, changes in the physical state of the material without any alteration in its chemical composition. Furthermore, they occur under certain pressure and temperature conditions that are characteristic for each substance. Understanding these changes is fundamental for the comprehension of many natural and industrial processes.
State changes of matter are one of the key topics in the study of sciences, particularly in chemistry and physics. Moreover, they have many practical applications that are of great importance for everyday life, such as the air conditioning system, which cools the air through evaporation, or the freezing of food to preserve it.
Understanding state changes is also essential for many industries, such as the food industry, the pharmaceutical industry, and even the aerospace industry. For example, distillation, which is a state change, is used in the industry to separate mixtures of liquids with different boiling points.
We suggest some resources to deepen the study on this topic:
- Book: "Chemistry: The Central Science" by Brown, LeMay, and Bursten.
- Video: The World of Chemistry - State Changes
- Website: State Changes of Matter - Brazil School
Practical Activity - Exploring State Changes
Project Objective
The project's objective is to investigate the state changes of matter and explain these transformations based on the submicroscopic constitution model. The activity will provide students with the opportunity to directly observe state changes and record their results.
Detailed Project Description
Students will be divided into groups of 3 to 5 members, and each group will simulate and document two state changes: (1) water solidification and (2) water evaporation.
Each group will have to thoroughly document all the steps of the experiment, explain the results obtained, and relate them to the concepts learned regarding state changes of matter. The practical activity should take between five to ten hours per participating student to be executed and will have a one-month deadline.
Required Materials
- Water
- Transparent containers (cups, bottles)
- Freezer
- Stove or Bunsen Burner and pot support
- Thermostat (optional)
- Camera or smartphone for photographic/video documentation
Detailed Step-by-Step
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Water Solidification: Fill a container with water and place it in the freezer. Document the initial state of the water (liquid), the time it takes to freeze, and the final state of the water (solid). Take photos or make a video of the process.
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Water Evaporation: Fill a container with water and place it on a heat source like a stove or Bunsen Burner. Monitor and document the water heating and its evaporation. Be cautious with the heat. Take photos or make a video of the process.
Project Deliverables
Students will have to deliver a report that will consist of:
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Introduction: Contextualization of the theme "State Changes of Matter," its relevance and application in everyday life, and the objective of this project.
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Development: In this section, students must theoretically explain the state changes of matter worked on in the project (solidification and evaporation), the experiment conducted, the methodology used, and finally, present and discuss the results obtained. The photos or videos of the experiments should be included in this section.
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Conclusion: Here, students must summarize the main points of the experience, explain the learnings obtained from the project, and draw conclusions about the state changes of matter.
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Bibliography: Students must cite the sources of information they used to elaborate the theoretical and practical part of the project.
With this activity, students will have the opportunity to test in practice the theoretical content studied, thus promoting a more meaningful learning. Furthermore, group work helps develop socio-emotional skills, such as communication, problem-solving, and time management.
