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Organic compounds are those that include carbon as a part of their structure. It is a branch of chemistry that deals with the synthesis of organic compounds.
- Organic compounds determine the structure, properties, and reactions of compounds.
- It consists of a carbon atom covalently bonded with four other carbon or hydrogen atoms.
- Open-chain compounds and cyclic compounds are two types of organic compounds.
- Benzene and Benzaldehyde are the most commonly used compounds.
The temperature at which the pressure exerted by the surroundings on a liquid equals the pressure exerted by the liquid's vapour; under this circumstance, adding heat causes the liquid to change into its vapour without increasing the temperature.
- This temperature is called the 'boiling point' of that liquid.
- In simple words, it is a process of changing liquid into a vapour state at a particular temperature.
- Various experiments can be conducted to determine the boiling point of organic compounds.
Key Terms: Determination of Boiling Point of Organic Compounds, Organic Compounds, Temperature, Benzene, Benzaldehyde, Boiling Point, Capillary Tube, Pressure, Thermometer
Aim
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The aim of the experiment is to determine the boiling point of organic compounds Benzene and Benzaldehyde.
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Material Required
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Following are the required materials for the experiment:
- An aluminium block
- Stand with Clamp
- Thermometer
- Tripod
- Kerosene Burner
- Capillary Tube
- Benzene
- Benzaldehyde
- Fusion Tube
Experimental Set-Up
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The experimental set-up is done as shown in the diagram below.
Experimental Setup
Procedure to determine boiling point of Benzene
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The procedure to determine boiling point of Benzene are as follows:
- First, close one end of a capillary tube by holding it in the fire.
- Next, rotate it for 2-3 minutes.
- Fill the fusion tube with some required ml of benzene liquid.
- Dip the sealed end of the capillary tube into the fluid in the fusion tube.
- Place the tube in one of the holes of the aluminium block's holes.
- Insert the thermometer into another hole in the tube.
- Make sure the liquid in the fusion tube is visible once it has been inserted into the hole.
- Place the tripod on top of the aluminium block.
- With the use of a kerosene stove, begin heating the block.
- As soon as consistent streams of bubbles emerge from the fluid in the fusion tube, take note of the temperature.
Procedure to determine boiling point of Benzaldehyde
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The procedure to determine boiling point of Benzene are as follows:
- Seal one side of the capillary tube.
- Next, hold one end of the tube in the flame for 2-3 minutes.
- Keep rotating the tube.
- Fill the fusion tube with some drops of Benzaldehyde.
- Put the capillary tube into Benzaldehyde liquid while keeping the closed end up.
- Place the thermometer in one of the aluminium block's holes.
- Simultaneously, insert the tubing into another hole.
- After inserting the fusion tube into the hole, check to see if the Benzaldehyde liquid is visible.
- Place the aluminium block on the tripod.
- Use the kerosene burner to start heating the block.
- Finally, as soon as the regular stream bubbles appear out of the liquid in the fusion tube, take note of the temperature.
Precautions
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Following precautions should be taken while performing the above experiment:
- Check to see if the capillary tubes are totally closed.
- It is also crucial to make sure the capillary tubes’ seal point is submerged in the liquid.
- Follow all safety measures and use adequate lab equipment.
- Uniformly heat the tube to avoid its breaking.
- Never force the glass tube to bend. If we try to do it, the tube might break.
Observations
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The obeservation regarding the determination of boiling point of organic compounds are as follows:
Temperature observation of Benzene
The table for temperature observation of Benzene are as follows:
| Temperature | Data |
|---|---|
| T1 | |
| T2 | |
| Boiling point of Benzene (T1 + T2 / 2 ) |
Temperature observation of Benzaldehyde
The table for temperature observation of Benzaldehyde are as follows:
| Temperature | Data |
|---|---|
| T1 | |
| T2 | |
| Boiling point of Benzaldehyde (T1 + T2 / 2 ) |
Things to Remember
- The determination of the boiling point of organic compounds helps understand the properties of compounds.
- The temperature at which an attractive force breaks and the molecule moves is known as the boiling point of an organic molecule.
- Organic substances' boiling points are determined by their molecular weight.
- The boiling point rises when the molecular weight rises.
- On the other hand, intramolecular covalent bonds are not disrupted at the boiling point.
- The functional groups of organic compounds and their forms (branched or unbranched) are crucial considerations in such experiments.
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Sample Questions
Ques. What effect does polarity have on the boiling point of organic compounds? (3 marks)
Ans. The attractive attraction among molecules in a liquid state is determined by the polarity of a molecule. The positive effect of one molecule is attracted to the negatively charged side of another molecule in polar substances. We may argue that polar molecules are pushed to opposing charges in this way. The functional group is crucial in determining the polarity. The boiling point rises as the polarity increases.
Ques. Explain why hydrocarbons have a lower boiling point than carboxylic acids? (2 marks)
Ans. Because of their ability to create hydrogen bonds, carboxylic acids have such a higher boiling point. These linkages provide these molecules more stability, allowing them to establish new bonds via dispersion forces.
Ques. What do you mean by compound's boiling point? (3 marks)
Ans. The temperature at which an attractive force or an intermolecular link breaks and the molecule moves is known as the boiling point of an organic molecule. Intramolecular covalent bonds, on the other hand, are not disrupted at the boiling point. Because molecular weight and boiling point are directly related, the boiling point of organic molecules is determined by their molecular weight. The boiling point of a chemical increases as its molecular weight increases.
Ques. What is the most important aspect in determining an organic compound's boiling point? (3 marks)
Ans. The form of the molecule, and whether or not it is branched, is the most essential aspect. When a molecule is much branched, it becomes spherical, which results in a reduced total surface area and a weaker Vanderwaal interaction between molecules, resulting in a lower boiling point. The surface area of an organic molecule with few branches is enormous, and the intra - molecular vanderwaal attraction is strong, resulting in a greater boiling point.
Ques. What happens if we boil water in a closed container at 100°C? (2 marks)
Ans. Liquids will not boil in closed containers. When the vapour pressure of the liquid and the air pressure are equal, boiling happens. As a result, liquid in a closed container will not boil.
Ques. What is Boiling Point? (1 mark)
Ans. The boiling point is the temperature at which the solution's vapour pressure equals the ambient vapour pressure.
Ques. Explain why, during steam distillation, an organic liquid evaporates at a temperature less than its boiling point? (1 mark)
Ans. It is because the total of the organic compounds and steam's vapour pressures in steam distillation should equal atmospheric pressure.
Ques. What method will you use to cleanse essential oils? (1 mark)
Ans. Because essential oils are volatile and insoluble in water, steam distillation is used to purify them.
Ques. Sublimation purifies what kinds of compounds? (1 mark)
Ans. Substances whose evaporation pressures equal atmospheric pressure at a temperature below their melting point.
Ques. Is it possible to quantify the amount of oxygen in an organic compound? (1 mark)
Ans. No, it's calculated by subtracting 100 from the fraction of all elements contained in an organic complex.
Ques. What is the boiling point of benzene and benzaldehyde? (1 mark)
Ans. The boiling point of benzene and benzaldehyde is 78°C and 178°C respectively.
Ques. Why carboxylic acids have a higher boiling point than hydrocarbons? (2 marks)
Ans. Hydrogen bonds, which carboxylic acids are capable of creating, stabilize the molecule and allow dispersion forces to build new bonds in the organic chain.
Ques. What is the difference between boiling points and melting points? (3 marks)
Ans. The difference between boiling points and melting points are as follows:
| Boiling Points | Melting Point |
|---|---|
| Boiling point convert liquid into gases state. | Melting point convert solid into liquid state. |
| It is dependent on external pressure. | It is not dependent on external pressure. |
| It is explained for liquids. | It is explained for solids. |
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