1. OBJECTIVE
These experiments address the physical and chemical properties of alkanes and alkenes. We will prove the non-polar nature of alkanes and alkenes through solubility tests in different solutions. The practical activity is divided into two moments. At first, we are going to check the density and solubility of hexane, cyclohexene, toluene and benzene in water and petroleum ether. In the second moment, we will verify the reactivity of the same reagents with an oxidizing solution of potassium permanganate and reaction with concentrated sulfuric acid. As part of the activities, you will have to perform pipetting and reagent handling procedures and take the necessary precautions when handling reagents that present toxicity or manipulation risk.
At the end of this experiment, you should be able to:
Plan and run experiments and interpret and analyze data;
correctly handle reagents using equipment and methodologies aimed at operator safety;
qualitatively identify characteristics about the solubility and density of solutions containing alkanes and alkenes;
identify the occurrence of chemical reactions through qualitative changes in the system, such as color change, release of gases and increase in temperature.
2. WHERE TO USE THESE CONCEPTS?
Alkanes and alkenes are classes of organic molecules that play important roles, including energy and solvent roles for a wide variety of reactions. Knowing the reactivity of alkanes and alkenes makes it possible to understand their applications and propose different uses for these substances. Biomedicine students are generally required to perform reactions involving organic solvents and other reagents that exhibit toxicity, such as acids. Thus, the laboratory practice involving these substances configures an instrument of familiarization with the manipulation processes of toxic reagents.
3. THE EXPERIMENT
In this experiment, you will use two pieces of equipment that are present in the vast majority of chemistry laboratories: the volumetric pipette and the test tubes. In the first step of the experiment, you will check the solubility of hexane, cyclohexene, toluene and benzene in different solvents. Here, you have to withdraw a previously defined volume of one of these solutions using a volumetric pipette and place it in a test tube. You will then use the pipette to add different solvents to these solutions. After adding these reagents, you must observe whether they are miscible with the starting solution. If not, you should check which one has the highest density, observing which of the solutions will be in the upper or lower region of the test tube. Later, using new test tubes, you will verify the reaction of these same alkanes and alkenes, but including the tomato extract, with a potassium permanganate solution and a concentrated sulfuric acid solution, always observing changes in the system, such as changes in coloration or release of gases.
4. SECURITY
In this practice, gloves, a long-sleeved lab coat and safety glasses must be worn. Personal protective equipment is important for handling toxic reagents such as volatile organic solvents and acids, considering the risk associated with handling them. Gloves and lab coat keep reagents from coming into contact with the skin, while goggles protect against solvent and acid splashes that can occasionally get into the eyes and cause serious damage.
5. SCENARIO
The environment for this experiment must be clean and airy. On the bench must be all the reagents that will be used, the volumetric pipette and the necessary amount of test tubes. The orders and instructions presented in the script must be followed.
These experiments address the physical and chemical properties of alkanes and alkenes. We will prove the non-polar nature of alkanes and alkenes through solubility tests in different solutions. The practical activity is divided into two moments. At first, we are going to check the density and solubility of hexane, cyclohexene, toluene and benzene in water and petroleum ether. In the second moment, we will verify the reactivity of the same reagents with an oxidizing solution of potassium permanganate and reaction with concentrated sulfuric acid. As part of the activities, you will have to perform pipetting and reagent handling procedures and take the necessary precautions when handling reagents that present toxicity or manipulation risk.
At the end of this experiment, you should be able to:
Plan and run experiments and interpret and analyze data;
correctly handle reagents using equipment and methodologies aimed at operator safety;
qualitatively identify characteristics about the solubility and density of solutions containing alkanes and alkenes;
identify the occurrence of chemical reactions through qualitative changes in the system, such as color change, release of gases and increase in temperature.
2. WHERE TO USE THESE CONCEPTS?
Alkanes and alkenes are classes of organic molecules that play important roles, including energy and solvent roles for a wide variety of reactions. Knowing the reactivity of alkanes and alkenes makes it possible to understand their applications and propose different uses for these substances. Biomedicine students are generally required to perform reactions involving organic solvents and other reagents that exhibit toxicity, such as acids. Thus, the laboratory practice involving these substances configures an instrument of familiarization with the manipulation processes of toxic reagents.
3. THE EXPERIMENT
In this experiment, you will use two pieces of equipment that are present in the vast majority of chemistry laboratories: the volumetric pipette and the test tubes. In the first step of the experiment, you will check the solubility of hexane, cyclohexene, toluene and benzene in different solvents. Here, you have to withdraw a previously defined volume of one of these solutions using a volumetric pipette and place it in a test tube. You will then use the pipette to add different solvents to these solutions. After adding these reagents, you must observe whether they are miscible with the starting solution. If not, you should check which one has the highest density, observing which of the solutions will be in the upper or lower region of the test tube. Later, using new test tubes, you will verify the reaction of these same alkanes and alkenes, but including the tomato extract, with a potassium permanganate solution and a concentrated sulfuric acid solution, always observing changes in the system, such as changes in coloration or release of gases.
4. SECURITY
In this practice, gloves, a long-sleeved lab coat and safety glasses must be worn. Personal protective equipment is important for handling toxic reagents such as volatile organic solvents and acids, considering the risk associated with handling them. Gloves and lab coat keep reagents from coming into contact with the skin, while goggles protect against solvent and acid splashes that can occasionally get into the eyes and cause serious damage.
5. SCENARIO
The environment for this experiment must be clean and airy. On the bench must be all the reagents that will be used, the volumetric pipette and the necessary amount of test tubes. The orders and instructions presented in the script must be followed.
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