Context

Organic Chemistry is the branch of chemistry that studies compounds containing carbon, an element that is the basis of all forms of life on Earth. In addition to being present in all living beings, organic compounds are also used in a multitude of industrial applications, such as the production of plastics, medicines, dyes, detergents, pesticides, among others.

The physical properties of organic compounds, such as boiling point, melting point, and density, are crucial for the study of their structure and, consequently, for predicting or explaining their behavior under different conditions. For example, substances with higher boiling points tend to be more stable at higher temperatures, while compounds with lower density tend to float in aqueous solutions, which can be a differential in processes of separating mixtures.

In everyday life, these properties are essential for determining the usefulness and application of various materials. Plastic, for example, is an organic compound whose physical properties make it a versatile material, capable of being molded into different shapes and resisting different temperature and pressure conditions.

Introduction

The physical properties of organic compounds are determined by different factors, including molecular structure (number and type of atoms), the type of bond between atoms (covalent, ionic, metallic bonds), molecule polarity, and intermolecular forces (hydrogen bonds, dipole-dipole forces, London forces).

The melting point is the temperature at which a substance changes from a solid to a liquid state. The boiling point is the temperature at which a substance changes from a liquid to a vapor state. These temperatures are directly influenced by the intermolecular forces present in the substance.

For example, substances with strong hydrogen bonds, such as water, have higher boiling points because more energy is required to break these bonds and transform the substance from liquid to vapor. In contrast, compounds with low polarity or with London forces (the weakest intermolecular forces) tend to have lower boiling and melting points.

Practical Activity: Investigating the Physical Properties of Organic Compounds

Project Objective

This project aims to observe, analyze, and discuss the physical properties (melting point, boiling point, and density) of different organic compounds.

Students should work in groups of 3 to 5 people. The project should last approximately one month, with an estimated workload of five to ten hours per student.

Detailed Project Description

Students should choose three different types of organic compounds available in the school's chemistry laboratory. Within these compounds, there must be variation in chemical characteristics, such as the presence of different functional groups.

Once the organic compounds are selected, students should conduct experiments to determine the physical properties of these compounds - melting point, boiling point, and density. It is essential that all experiments be conducted following safety regulations within a laboratory.

Required Materials

• Three types of organic compounds
• Precision balance
• Graduated cylinder
• Test tubes
• Bunsen burner or hot plate
• Thermometer
• Safety equipment (goggles, gloves, lab coat)

Detailed Step-by-Step

1. Choose the three organic compounds to be analyzed.
2. Using the precision balance, measure the amount of each compound for the experiments.
3. Use the knowledge acquired in theoretical classes to predict the physical properties of the compounds.
4. Perform the experiment to determine the melting point of each compound.
5. Perform the experiment to determine the boiling point of each compound.
6. Perform the experiment to determine the density of each compound.
7. Record all results obtained and compare them with the predictions made in step 3 of the practical activity.

Project Deliverables and Documentation

Upon completing the practical parts of the project, students should prepare a written report containing the following topics:

• Introduction: In this section, students should contextualize the topic addressed, the relevance of organic compounds and their physical properties, as well as the objective of this project.
• Development: Here, students should explain the theory behind the study of the physical properties of organic compounds. Then, they should detail the experiments conducted: which compounds were chosen, how the experiments were conducted, what results were obtained, and how these results relate to the initial predictions made in step 3 of the practical activity.
• Conclusion: Students should conclude the work by summarizing their main points, explaining the learnings obtained, and the conclusions drawn from the project results. Additionally, they should reflect on the importance of understanding the physical properties of organic compounds in relation to their everyday applications.
• Bibliography: Students should indicate the sources they relied on to work on the project such as books, web pages, videos, among others.

This report should be submitted to the teacher at the end of the project for evaluation.