Contextualization

Vapor pressure is a fundamental physical property in chemistry that affects how substances behave and interact. To understand what vapor pressure is, imagine yourself on a very hot day trying to cool off with a bottle of water. You open the bottle and some of the water evaporates. This happens because of vapor pressure: the tendency of a substance to transition from the liquid state to the vapor state. This tendency is greater when the substance molecules have more energy, meaning when the temperature is higher.

But what determines the vapor pressure of a substance? Several factors come into play: the nature of the substance, the temperature, and even the presence of other substances in the mixture. All these variables together create a complex dance of molecules that determines whether the substance will evaporate or not.

Now, you might be wondering, 'Why is vapor pressure important? I've never heard of it before.' Vapor pressure has many practical applications. It is crucial in determining the effectiveness of various products we use daily. For example, food engineers use vapor pressure to determine the amount of aromas that will be released from a food when it is cooked. Doctors use vapor pressure to determine the amount of medication a patient should receive.

For this project, you will be challenged to investigate vapor pressure: what it is, how it is determined, and how it affects our lives. You will have fun conducting experiments and discussing the results with your colleagues.

To prepare for this, I suggest you take a look at the following resources:

• Vapor Pressure - Khan Academy
• Vapor Pressure - Toda Matéria
• Vapor Pressure - Wikipedia

Practical Activity

Activity Title: Investigating Vapor Pressure

Project Objective

The activity focuses on conducting experiments to investigate vapor pressure, taking into account different temperatures and substances. In addition, students must create a graph relating vapor pressure and temperature for each substance and mathematically explain these relationships.

Detailed Project Description

Each group of 3 to 5 students will need to choose at least two different substances (for example, water and isopropyl alcohol) and conduct an experiment to determine their vapor pressure. Students will also need to investigate how temperature affects vapor pressure and how vapor pressure changes in a mixture of these substances. In addition to conducting the experiment, students should research the behavior of the chosen substances, how they interact, and how this can influence the results obtained.

Required Materials

To conduct the experiment, students will need the following materials:

1. Two different liquid substances.
2. A thermometer.
3. A barometer.
4. A sealed container where the substances can be placed.
5. A heating plate.

Detailed Step-by-Step for Activity Execution

1. Choose two different substances.
2. Place one of the substances in the sealed container and record the temperature and pressure in the container.
3. Heat the substance slowly and record the temperature and pressure every 5 minutes.
4. Repeat steps 2 and 3 for the second substance.
5. Mix the two substances in the sealed container and repeat step 3.
6. Create three different graphs, one for each substance and one for the mixture of the two, plotting vapor pressure against temperature.
7. Analyze the obtained graphs and discuss the results.

Project Deliverables

Each group must deliver:

1. Project Report: Students must create a detailed report of the experiment.

   • Introduction: Provide context on the topic, its real-world application, and the project's objective.
   • Development: Explain the theory behind vapor pressure, detail the experiment, the methodology used, and present and discuss the results obtained. The constructed graphs should be included in this section.
   • Conclusion: Conclude the work by summarizing the main points, the conclusions drawn from the project, and the learnings obtained.
   • Bibliography: Indicate the references used for the work, such as books, websites, videos, etc.

2. Oral Presentation: Students must prepare an oral presentation of the project for the class, focusing on explaining the conducted experiment, presenting the graphs, and discussing the conclusions reached.

We recommend a total duration of at least 12 hours for the activity, considering the experiment execution, data analysis, report elaboration, and presentation preparation.