Contextualization

Chemistry is a discipline that permeates many areas of our daily lives, one of them being the famous concept of 'Chemical Equilibrium'. In a chemical reaction, both the reactants and the products tend to exist in a constant state, that is, in equilibrium. However, this equilibrium does not necessarily mean that the quantities of reactants and products are equal, but that their concentrations do not change over time. Understanding chemical equilibrium is essential to realize how reactions occur in our daily lives and to manipulate chemical reactions in laboratories and industries.

The equilibrium constant (K) is a mathematical expression that describes the relationship between the concentrations of the reactants and products in a reaction at equilibrium. This is an important theoretical concept that allows predicting the outcome of any chemical reaction. Calculating K, its interpretation, and using it to control the results of reactions will be the main topics of this project.

Chemical reactions in equilibrium are everywhere, from our breathing to the formation of clouds in the atmosphere. For example, the process of photosynthesis, which is vital for life on Earth, is a reaction in equilibrium. Furthermore, many industrial processes, such as the production of fertilizers, rely on controlling chemical equilibrium. Therefore, understanding chemical equilibrium and how to manipulate it is essential for society and for various disciplines, including medicine, biology, engineering, and, of course, chemistry.

Practical Activity

Activity Title: Manipulating Equilibrium: The Case of Crushed Cans

Project Objective

The objective of this project is to provide a practical experience to understand the concept of chemical equilibrium, how to calculate the equilibrium constant, and how external factors can influence equilibrium.

Detailed Project Description

Students will be divided into groups of 3 to 5 people. Each group will receive an empty soda can, a balloon, a thermometer, water, and ice. An experiment will be conducted to explore the equilibrium reaction that occurs inside the soda can when varying the temperature. Students will record their observations and calculations and make a PowerPoint presentation to share their findings with the class.

Required Materials

For each group of students, the following materials will be needed:

• An empty soda can with a lid (can be a common aluminum soda can).
• A balloon that fits the can's opening.
• A thermometer.
• Water.
• Ice.
• A notebook to record observations and calculations.

Detailed Step-by-Step for Activity Execution

1. Theoretical Understanding: Before starting the experiment, students should research to fully understand the concept of chemical equilibrium and how temperature affects equilibrium. This research should be documented and properly referenced.

2. Experiment Setup: Fill the soda can with about 20 ml of water. Place the balloon on the can's opening. Check the room temperature with the thermometer and record it.

3. Initial Observation: Observe the balloon and record any changes in its shape or size. This will be your initial observation.

4. Temperature Variation: Place the soda can in an ice bath to cool it. Continue observing and recording any changes in the balloon's shape or size. Measure the temperature again and record it.

5. Results Analysis: Students should then analyze their observations and use them to formulate a hypothesis about the effect of temperature on the chemical equilibrium inside the can. They should use their research for theoretical support and calculate the equilibrium constant for the different temperatures.

6. Presentation Preparation: Each group should prepare a PowerPoint presentation explaining the experiment, their observations, and conclusions. The presentation should include a detailed explanation of the calculations used to determine the equilibrium constant and how the temperature change affected the chemical equilibrium.

7. Report Writing: Alongside the presentation, students should write the final report following the structure specified in the introduction of this project (Introduction, Development, Conclusion, and Bibliography). The report should include all details of this experiment, including preparation, observations, analysis, and conclusions.

Students will have one month to complete the work, from the initial research to the report writing. This time should be efficiently divided among all stages of the activity.

Project Deliverables

• A final report in Word document format, containing the four main sections (Introduction, Development, Conclusions, and Bibliography). The report should detail the theory of chemical equilibrium, the experiment description, the methodology used, the presentation and analysis of the results obtained, and the conclusions drawn based on the results.
• A PowerPoint presentation sharing the group's findings with the rest of the class. This presentation will be held in the last week of the project deadline.